Donald Trump has ordered an additional 3,000 active-duty troops to the U.S.-Mexico border as he seeks to clamp down on illegal immigration and fulfil a central promise of his campaign, US officials have confirmed. His defence secretary, Pete Hegseth, has ordered elements of a Stryker brigade combat team and a general support aviation battalion for the mission, the Pentagon announced.

The forces will arrive along the nearly 2,000-mile border in the coming weeks. While the US Department of Defense did not specify the size of the deployment, it was put at about 3,000 by officials, who spoke on condition of anonymity.

The Strykers are medium-armoured wheeled personnel carriers which are also used by US troops in Europe.

So far, around 9,200 U.S. troops are already at the southern border, including 4,200 deployed under federal orders and about 5,000 National Guards under the control of governors.

The new troops will “reinforce and expand current border security operations to seal the border and protect the territorial integrity of the United States,” the Pentagon said.

Trump is determined to expand the military’s role in his effort to shut down the border and send detained migrants back to their home countries.

Military personnel have been sent to the border almost continuously since the 1990s to help address migration, drug trafficking and transnational crime.