WASHINGTON (Reuters) – The total number of U.S. troops heading to the border with Mexico could be in the thousands but there is no firm figure yet, a U.S. official told Reuters on Monday, offering a much higher estimate than the 800 to 1,000 initially forecast.

The Pentagon declined comment on potential troop numbers, saying planning was still underway for a mission that aims to bolster President Donald Trump’s battle against migrants trekking toward the United States.

(Reporting by Phil Stewart; Editing by Chizu Nomiyama)