Speaker 1: Breaking news involving the southern border tonight. President Trump set to deploy an additional 1,500 troops to the border. Here's our chief White House correspondent, Mary Bruce, on what those troops will do.

Speaker 2: Tonight, up to 1,500 troops, a mix of active duty Army and Marines, heading to the southern border after the president declared a national emergency.

Speaker 3: I will send troops to the southern border to repel the disastrous invasion of our country.

Speaker 2: The troops given 24 hours to deploy, military police units, combat engineers, and intelligence specialists to aid with detection and monitoring, according to the Pentagon. Troops also tasked with helping to construct physical barriers along the border, but a military official insists none will participate in law enforcement. Also part of the effort, military aircraft to support deportation flights. We asked the new White House press secretary what to expect.

Speaker 4: Caroline, what are they doing on the border? What is their mission exactly? Securing the southern border and deporting illegal immigrants from this country. You will be returned home. You will be arrested. You will be prosecuted. Do not come.

Speaker 2: We will shut the border. The surge in forces comes as the situation on the border has improved steadily since former President Biden announced new asylum restrictions last spring. Encounters between border patrol and migrants down 60%. Today's move, just part of Trump's promised immigration crackdown. Refugee arrivals to the U.S. now suspended until further notice. The app used by migrants to make appointments to seek asylum shut down. Tens of thousands of migrants who had appointments now in limbo. Trump also declaring an end to birthright citizenship, even though it's protected by the 14th Amendment. 22 states and two cities have now filed lawsuits to block the move, estimating that some 150,000 children could be impacted each year. And David, tonight the Pentagon hasn't put a dollar figure yet on how much this operation on the border will cost, but it will likely be hefty. And tonight, a senior official telling us this is just the start.

Speaker 1: David. Mary Bruce, live at the White House. Mary, thank you.