According to a US Department of Defense statement, additional forces will be deployed to the nation’s southwest border with Mexico for three months as a means of providing support to customs and border agents.

The move will lead to a rise in the number of active US forces providing support for Customs and Border Protection (CBP) agents, to approximately 4,350, Reuters reported.

"The Department of Defense will deploy approximately 3,750 additional U.S. forces to provide the additional support to CBP at the southwest border… This will raise the total Active Duty forces supporting CBP at the border to approximately 4,350," the Pentagon's press service said.    

Besides that, a mobile surveillance capability will be positioned at the border and around 150 miles (241 kilometers) of concertina wire will be pulled between the ports of entry before the end of September.

On January 31, US President Donald Trump announced in a tweet the upcoming deployment of US forces to Mexican border "to stop the attempted Invasion of Illegals."

In late January 2019, Secretary of Defence Patrick Shanahan announced that the Pentagon has been preparing to send "several thousand" additional troops to the Mexico-US border, answering a US Department of Homeland Security (DHS) call for assistance in monitoring and "laying down more concertina wire".

Earlier, the undersecretary of defense for policy, John Rood, told Congress that US officials are tracking three migrant caravans from Central America allegedly making their way toward the US-Mexican border, the largest of which is said to have over 12,000 would-be immigrants.    

Initially the deployment of active-duty US forces was approved by the Pentagon in October 2018 and the decision was embraced by Trump supporters in Congress, according to Reuters. 

The request for funding for additional security and the construction of a wall along the US-Mexico border has been a sticking point in negotiations between Trump and the Democrats, and led to a 35-day partial government shutdown.

On 25 January, Trump signed a temporary three-week budget to end the shutdown without getting the $5.7 billion he had demanded from the Congress for a wall along the southern border. Trump is reportedly expected to continue talks with the Democrats on the full-fledged budget within next three weeks.