Honduran migrants heading in a caravan to the United States, walk in direction to Tecun Uman -the border with Mexico,- as they leave Guatemala City, on October 18, 2018. - US President Donald Trump threatened Thursday to send the military to close its southern border if Mexico fails to stem the "onslaught" of migrants from Central America, in a series of tweets that blamed Democrats ahead of the midterm elections. (Photo by ORLANDO SIERRA / AFP)