U.S. sending 3,750 more troops to Mexico border

The Pentagon is sending 3,750 U.S. forces to the southwest U.S. border with Mexico for three months to provide additional support to border agents, the Department of Defence said on Sunday.

The deployment will raise the total number of active-duty forces supporting Customs and Border Protection agents there to approximately 4,350, it said.

The Pentagon disclosed the official figure days after a Democratic lawmaker said about 3,500 extra troops would be deployed.

President Donald Trump, who has portrayed the situation at the border as a crisis, was expected to talk about immigration and his proposal for a wall along the U.S. border with Mexico during the annual State of the Union address on Tuesday.

Trump's demand that money for the wall be included in spending legislation prompted an impasse with Democrats that led to a 35-day partial federal government shutdown that ended on Jan. 25.

If lawmakers cannot reach a deal on the border security situation by Feb. 15, Trump has threatened to let the government shut down again or to declare a national emergency as a way to circumvent Congress and get his wall money.

"I don't take anything off the table," he said in a CBS interview broadcast on Sunday.

The Pentagon first approved the high-profile deployment of active-duty U.S. troops to the Mexico border in October, before the U.S. midterm congressional elections. The move was embraced by President Donald Trump's supporters, including fellow Republicans in Congress.

Critics called the deployment a political stunt and scoffed at Trump's comparisons of caravans of Central American migrants, including women and children, to an "invasion."

The Pentagon says the U.S. military will operate mobile surveillance cameras in Arizona, California, New Mexico and Texas, a mission scheduled to run through Sept. 30. Some of the additional troops will also string up 240 kilometres of concertina wire.

Acting Defence Secretary Patrick Shanahan approved the deployment on Jan. 11, according to the statement. U.S. Rep. Adam Smith, chairman of the House of Representatives armed services committee, first disclosed plans to send more troops on Thursday.

Smith criticized senior Pentagon officials for failing to disclose the information during a hearing before his committee in Congress on the issue just two days earlier.