A new group of migrants bound for the United States set off from El Salvador on Sunday, following thousands of other Central Americans fleeing poverty and violence who have taken similar journeys in recent weeks.
The group of more than 300 Salvadorans left the capital San Salvador on Sunday. A larger group of mostly Hondurans, estimated to number at least 3,500, who left their country in mid-October and are now in southern Mexico, has become a key issue in U.S. congressional elections.
A third group has been moving through Guatemala, at one point numbering more than 1,000 people before beginning to fragment. Hundreds of that group broke through a Guatemala border gate in Tecun Uman, and on Sunday afternoon were on the bridge into Mexico.
Trump has threatened to shut down the border with Mexico and last week said he would send troops. On Friday, Defense Secretary Jim Mattis authorized the use of troops and other military resources at the U.S.-Mexico border.