Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

(191203) -- LONDON, Dec. 3, 2019 (Xinhua) -- NATO General Secretary Jens Stoltenberg(L) meets with U.S. President Donald Trump in London, Britain, on Dec. 3, 2019. -EDITORIAL USE ONLY-(No material produced by NATO is to be sold, used for outside advertising or promotional purposes of any kind. Photos, videos and articles are released under the legally recognized terms of "Fair Use" to members of the press, academia, non-profits and the general public. No material is to be used in programs, articles or online publications of any kind that defame NATO or its member countries.) (Photo by NATO/Handout via Xinhua) Xinhua News Agency / eyevine

Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

Police near Watford's grove hotel where the NATO summit is being held. Donald Trump has arrived in the UK for the third time since his election for a Nato summit on international security. The US President landed at Stansted Airport just before 10pm on Monday, December 2 for a two-day visit which includes a reception at Buckingham Palace. ? Jeremy Selwyn / Evening Standard / eyevine

(191203) -- LONDON, Dec. 3, 2019 (Xinhua) -- NATO General Secretary Jens Stoltenberg(L) meets with U.S. President Donald Trump in London, Britain, on Dec. 3, 2019. -EDITORIAL USE ONLY-(No material produced by NATO is to be sold, used for outside advertising or promotional purposes of any kind. Photos, videos and articles are released under the legally recognized terms of "Fair Use" to members of the press, academia, non-profits and the general public. No material is to be used in programs, articles or online publications of any kind that defame NATO or its member countries.) (Photo by NATO/Handout via Xinhua) Xinhua News Agency / eyevine

Russian President Vladimir Putin meets with top military officials in Sochi on December 3, 2019. - President Vladimir Putin on December 3, 2019 said Russia is open to cooperation with NATO as a two-day summit of the Western alliance opened in London. (Photo by Mikhail KLIMENTYEV / SPUTNIK / AFP)

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Angela Merkel arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Angela Merkel arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. French President Emmanuel Macron arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Angela Merkel , Emmanuelle Macron and Recep Erdogan arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Emmanuelle Macron leaving a meeting with Boris Johnson at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Emmanuelle Macron leaving a meeting with Boris Johnson at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

03 December 2019, Great Britain, London: Emanuel Macron, President of France, arrives at a meeting of the four heads of government of Germany, France, England and Turkey at Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Emanuel Macron, President of France, arrives at a meeting of the four heads of government of Germany, France, England and Turkey at Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Emanuel Macron, President of France, arrives at a meeting of the four heads of government of Germany, France, England and Turkey at Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Emanuel Macron, President of France, arrives at a meeting of the four heads of government of Germany, France, England and Turkey at Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Federal Chancellor Angela Merkel (CDU) comes to a meeting of the four heads of government of Germany, France, England and Turkey in Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Emmanuelle Macron leaving a meeting with Boris Johnson at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Emmanuelle Macron leaving a meeting with Boris Johnson at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. French President Emmanuel Macron arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. French President Emmanuel Macron arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. French President Emmanuel Macron arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

03 December 2019, Great Britain, London: Recep Tayyip Erdogan, President of Turkey, arrives at a meeting of the four heads of government of Germany, France, England and Turkey at Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Recep Tayyip Erdogan, President of Turkey, arrives at a meeting of the four heads of government of Germany, France, England and Turkey at Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Recep Tayyip Erdogan, President of Turkey, arrives at a meeting of the four heads of government of Germany, France, England and Turkey at Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Angela Merkel , Emmanuelle Macron and Recep Erdogan arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump at a tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump with Queen Elizabeth II and Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at a reception at Buckingham Palace in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019 Donald Trump and his wife Melania arriving for a reception at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump with Queen Elizabeth II and Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at a reception at Buckingham Palace in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Queen Elizabeth II stands with Nato Secretary General Jens Stoltenberg (centre) and the Prime Minisiter of Greece, Kyriakos Mitsotakis and his wife Mareva Grabowski at a reception at Buckingham Palace in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump at a tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump at a tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump at a tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump arrive for tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump arrive for tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump arrive for tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump arrive for tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump arrive for tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump arrive for tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump arrive for tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump arrive for tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump arrive for tea hosted by Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at Clarence House in London on the first day of NATO Summit Picture by i-Images / Pool

03 December 2019, Great Britain, London: Federal Chancellor Angela Merkel (CDU) comes to a meeting of the four heads of government of Germany, France, England and Turkey in Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Recep Tayyip Erdogan, President of Turkey, is leaving 10 Downing Street after a meeting of the four heads of government of Germany, France, England and Turkey before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: German Chancellor Angela Merkel (CDU) leaves 10 Downing Street after a meeting of the four heads of government of Germany, France, England and Turkey before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: German Chancellor Angela Merkel (CDU) leaves 10 Downing Street after a meeting of the four heads of government of Germany, France, England and Turkey before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

Image ?Licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Downing St Reception ahead of NATO summit. Picture by Martyn Wheatley / i-Images

03 December 2019, Great Britain, London: The flags of NATO and the member states of the waving before the start of the NATO summit in front of Buckingham Palace. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

dpatop - 03 December 2019, Great Britain, London: Federal Chancellor Angela Merkel (CDU) comes to a meeting of the four heads of government of Germany, France, England and Turkey in Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Chancellor Angela Merkel (CDU) comes to a meeting of the four heads of government of Germany, France, England and Turkey in Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. President of Turkey Recep Tayyip Erdo?an arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. President of Turkey Recep Tayyip Erdo?an arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Angela Merkel , Emmanuelle Macron and Recep Erdogan arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Angela Merkel , Emmanuelle Macron and Recep Erdogan arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Angela Merkel , Emmanuelle Macron and Recep Erdogan arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Angela Merkel , Emmanuelle Macron and Recep Erdogan arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

03 December 2019, Great Britain, London: The entrance to Downingstra?e 10, taken before a meeting of Chancellor Merkel (CDU) and the four heads of government of Germany, France, England and Turkey before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Federal Chancellor Angela Merkel (CDU) comes to a meeting of the four heads of government of Germany, France, England and Turkey in Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Federal Chancellor Angela Merkel (CDU) comes to a meeting of the four heads of government of Germany, France, England and Turkey in Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

03 December 2019, Great Britain, London: Federal Chancellor Angela Merkel (CDU) comes to a meeting of the four heads of government of Germany, France, England and Turkey in Downingstrasse 10 before the start of the actual NATO summit. The subject of the meeting will be the conflict in Syria. The meeting of heads of state and government will celebrate the 70th anniversary of the military alliance. Photo: Michael Kappeler/dpa

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. US President Donald Trump and First Lady Melania Trump with Queen Elizabeth II and Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall at a reception at Buckingham Palace in London on the first day of NATO Summit Picture by i-Images / Pool

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Angela Merkle , Emmanuelle Macron and Recep Erdogan arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

Image licensed to i-Images Picture Agency. 03/12/2019. London, United Kingdom. Angela Merkel , Emmanuelle Macron and Recep Erdogan arriving for a meeting at No10 Downing Street in London, on the first day of the NATO Summit. Picture by Stephen Lock / i-Images

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. 02 Dec 2019 Pictured: Marine One lands on the South Lawn of the White House in Washington D.C., U.S., as United States President Donald J. Trump and First lady Melania Trump prepare to depart for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. Photo credit: Stefani Reynolds - CNP / MEGA TheMegaAgency.com +1 888 505 6342

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. 02 Dec 2019 Pictured: United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. Photo credit: Stefani Reynolds - CNP / MEGA TheMegaAgency.com +1 888 505 6342

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. 02 Dec 2019 Pictured: United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. Photo credit: Stefani Reynolds - CNP / MEGA TheMegaAgency.com +1 888 505 6342

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. 02 Dec 2019 Pictured: United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. Photo credit: Stefani Reynolds - CNP / MEGA TheMegaAgency.com +1 888 505 6342

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. 02 Dec 2019 Pictured: United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. Photo credit: Stefani Reynolds - CNP / MEGA TheMegaAgency.com +1 888 505 6342

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. 02 Dec 2019 Pictured: United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. Photo credit: Stefani Reynolds - CNP / MEGA TheMegaAgency.com +1 888 505 6342

02 December 2019, Great Britain, London: A flag of the NATO (r-l) and the NATO member states USA as well as Turkey are hoisted at the "Mall" in front of Buckingham Palace. From 3 December to 4 December, the heads of government of the member countries of the defence alliance will meet at the NATO summit in London. Photo: Michael Kappeler/doa/dpa

U.S. President Donald Trump speaks to the media on the South Lawn of the White House in Washington before his departure for NATO summit in London on December 2, 2019. Photo by Yuri Gripas/ABACAPRESS.COM

U.S. President Donald Trump speaks to the media on the South Lawn of the White House in Washington before his departure for NATO summit in London on December 2, 2019. Photo by Yuri Gripas/ABACAPRESS.COM

U.S. President Donald Trump speaks to the media on the South Lawn of the White House in Washington before his departure for NATO summit in London on December 2, 2019. Photo by Yuri Gripas/ABACAPRESS.COM

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. CAP/MPI/RS ??RS/MPI/Capital Pictures

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. CAP/MPI/RS ??RS/MPI/Capital Pictures

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. CAP/MPI/RS ??RS/MPI/Capital Pictures

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. CAP/MPI/RS ??RS/MPI/Capital Pictures

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. CAP/MPI/RS ??RS/MPI/Capital Pictures

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. CAP/MPI/RS ??RS/MPI/Capital Pictures

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. 02 Dec 2019 Pictured: First lady Melania Trump walks to Marine One on the South Lawn of the White House in Washington D.C., U.S., as she and United States President Donald J. Trump depart for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP. Photo credit: Stefani Reynolds - CNP / MEGA TheMegaAgency.com +1 888 505 6342

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP | usage worldwide

United States President Donald J. Trump speaks to members of the media on the South Lawn of the White House in Washington D.C., U.S., as he departs for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP | usage worldwide

First lady Melania Trump walks to Marine One on the South Lawn of the White House in Washington D.C., U.S., as she and United States President Donald J. Trump depart for the NATO summit in London, United Kingdom, on Monday, December 2, 2019. Credit: Stefani Reynolds / CNP | usage worldwide