Trump told reporters at the White House on Wednesday that "we'll go up to anywhere between 10 and 15,000 military personnel on top of Border Patrol, ICE and everybody else at the border."
He says the move would be aimed at preventing the entry of a caravan of migrants traveling from Central America. The caravan is still nearly 1,000 miles (1,600 kilometers) from the border.
MORE: Migrant caravan of Central Americans moving through Mexico to US border, explained
Trump says that the U.S. was "going to be prepared" and that the migrants are "not coming into our country."
Currently there are 2,100 National Guard helping at the border. The Pentagon says an additional 5,200 active-duty troops could join them.
DEVELOPING...We will add more details to this report as they become available.