In this handout photo provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskiy lays flowers at a memorial of the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran, at Borispil international airport outside in Kyiv, Ukraine, Thursday, Jan. 9, 2020. A Ukrainian passenger jet carrying 176 people has crashed just minutes after taking off from the Iranian capital's main airport, turning farmland on the outskirts of Tehran into fields of flaming debris and killing all on board. (Ukrainian Presidential Press Office via AP)

Wax from melted candles next to flowers are placed at the Canadian Embassy during a national day of mourning in Kyiv, Ukraine, Thursday, Jan. 9, 2020, for the victims of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran. A Ukrainian passenger jet carrying 176 people crashed just minutes after taking off from the Iranian capital's main airport, Wednesday, turning farmland on the outskirts of Tehran into fields of debris and killing all on board. (AP Photo/Efrem Lukatsky)

People look at a memorial at Borispil international airport outside in Kyiv, Ukraine, Thursday, Jan. 9, 2020, for the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran. The crew of a Ukrainian jetliner that crashed in Iran, killing all 176 people on board, never made a radio call for help and was trying to turn back for the airport when the burning plane went down, an initial Iranian investigative report said Thursday. (AP Photo/Efrem Lukatsky)

People look at a memorial at Borispil international airport outside in Kyiv, Ukraine, Thursday, Jan. 9, 2020, for the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran. The crew of a Ukrainian jetliner that crashed in Iran, killing all 176 people on board, never made a radio call for help and was trying to turn back for the airport when the burning plane went down, an initial Iranian investigative report said Thursday. (AP Photo/Efrem Lukatsky)

People look at a memorial at Borispil international airport outside in Kyiv, Ukraine, Thursday, Jan. 9, 2020, for the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran. The crew of a Ukrainian jetliner that crashed in Iran, killing all 176 people on board, never made a radio call for help and was trying to turn back for the airport when the burning plane went down, an initial Iranian investigative report said Thursday. (AP Photo/Efrem Lukatsky)

People look at a memorial at Borispil international airport outside in Kyiv, Ukraine, Thursday, Jan. 9, 2020, for the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran. The crew of a Ukrainian jetliner that crashed in Iran, killing all 176 people on board, never made a radio call for help and was trying to turn back for the airport when the burning plane went down, an initial Iranian investigative report said Thursday. (AP Photo/Efrem Lukatsky)

People look at a memorial at Borispil international airport outside in Kyiv, Ukraine, Thursday, Jan. 9, 2020, for the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran. The crew of a Ukrainian jetliner that crashed in Iran, killing all 176 people on board, never made a radio call for help and was trying to turn back for the airport when the burning plane went down, an initial Iranian investigative report said Thursday. (AP Photo/Efrem Lukatsky)

People look at a memorial at Borispil international airport outside in Kyiv, Ukraine, Thursday, Jan. 9, 2020, for the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran. The crew of a Ukrainian jetliner that crashed in Iran, killing all 176 people on board, never made a radio call for help and was trying to turn back for the airport when the burning plane went down, an initial Iranian investigative report said Thursday. (AP Photo/Efrem Lukatsky)

This handout picture taken and released by the Ukrainian presidential press service shows Ukraine's President Volodymyr Zelensky placing flowers at a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 9, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran on January 8, 2020 killing all 176 people on board, mainly Iranians and Canadians. (Photo by HO / UKRAINIAN PRESIDENTIAL PRESS SERVICE / AFP) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / UKRAINIAN PRESIDENTIAL PRESS SERVICE / HO " - NO MARKETING - NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS

Relative and friends of the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran, lay flowers at a memorial inside Borispil international airport outside Kyiv, Ukraine, Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying 176 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard, Iranian state TV and officials in Ukraine said. (AP Photo/Efrem Lukatsky)

Flowers and candles are placed in front of portraits of the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran, at a memorial inside Borispil international airport outside Kyiv, Ukraine, Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying 176 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard, Iranian state TV and officials in Ukraine said. (AP Photo/Efrem Lukatsky)

Relatives of the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran, mourn at a memorial inside Borispil international airport outside Kyiv, Ukraine, Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying 176 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard, Iranian state TV and officials in Ukraine said. (AP Photo/Efrem Lukatsky), APTOPIX

A relative of one of the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran, lays flowers at a memorial inside Borispil international airport outside Kyiv, Ukraine, Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying 176 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard, Iranian state TV and officials in Ukraine said. (AP Photo/Efrem Lukatsky)

A colleague of one of the flight crew members of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran, lights candles at a memorial inside Borispil international airport outside Kyiv, Ukraine, Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying 176 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard, Iranian state TV and officials in Ukraine said. (AP Photo/Efrem Lukatsky)

Two women mourn standing in front of a memorial for the flight crew of the Ukrainian 737-800 plane that crashed on the outskirts of Tehran, inside Borispil international airport outside Kyiv, Ukraine, late Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying 176 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard, Iranian state TV and officials in Ukraine said. (AP Photo/Efrem Lukatsky)

A candle is placed on a table bearing photos of some of the victims of a Ukraine International Airlines passenger flight that crashed after takeoff near Tehran, Iran, as members of Toronto's Iranian community attend a vigil in Toronto, Wednesday, Jan. 8, 2020. (Chris Young/The Canadian Press via AP)

Relatives of the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, react by a memorial at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

A man places flowers at a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

A man looks on by a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

A man sits by a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

Flight staffers place candles in front of a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

People react by a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

A man places flowers at a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

A flight staffer arranges candles at a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

People react in front of a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

A man reacts in front of a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

A woman reacts in front of a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

Portraits of the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, are seen at a memorial at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

A woman places flowers at a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - An Ukrainian airliner crashed shortly after take-off from Tehran on January 8, 2020 killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)

TOPSHOT - A man reacts in front of a memorial for the victims of the Ukraine International Airlines Boeing 737-800 crash in the Iranian capital Tehran, at the Boryspil airport outside Kiev on January 8, 2020. - A Ukrainian airliner crashed shortly after take-off from Tehran Wednesday killing all 176 people on board, in a disaster striking a region rattled by heightened military tensions. (Photo by Sergei SUPINSKY / AFP)