The Pentagon is sending about 3,000 additional troops to the southwestern border, rushing to comply with President Trump’s order to increase the military’s role in stemming the flow of migrants into the United States.
Armed infantry and support troops from the 4th Infantry Division at Fort Carson in Colorado — one of the Army’s most seasoned combat units — are expected to deploy within days, two Pentagon officials said on Saturday, after Mr. Trump’s declaration on his first day in office that U.S. military forces would confront what he called an “invasion” of migrants, drug cartels and smugglers.
Combined with 1,100 support troops from the military’s Northern Command announced on Friday, and the recently arrived headquarters personnel from the 10th Mountain Division at Fort Drum, N.Y., the reinforcements announced on Saturday would bring the total number of active-duty troops on the border to about 9,000, Defense Department officials said. The Washington Post reported the additional troop mobilization earlier.
“These forces will arrive in the coming weeks, and their deployment underscores the department’s unwavering dedication to working alongside the Department of Homeland Security to secure our southern border and maintain the sovereignty, territorial integrity and security of the United States under President Trump’s leadership,” the Pentagon said in a statement on Saturday.
This will be the second major wave of active-duty troops sent to secure the border since Mr. Trump took office on Jan. 20. About 1,600 Marines and Army soldiers arrived soon after the inauguration, joining 2,500 Army reservists called to active duty who were already there.
Dispatching large numbers of frontline combat forces indicates that Mr. Trump is breaking with past presidents’ recent practice of mostly limiting deployments along the U.S.-Mexico border to small numbers of active-duty soldiers and reservists.
So far, the active-duty troops have been helping to build barriers and support law-enforcement agencies, as have active-duty and reservist forces sent to the border in past years, including during Mr. Trump’s first term.
But Defense Secretary Pete Hegseth said on his first full official day on the job in January that “whatever is needed at the border will be provided.” He did not rule out Mr. Trump’s invoking the Insurrection Act, a more than 200-year-old law, to allow the use of armed forces for law enforcement duty.
Taking such an action would plunge the military into politically charged territory that has given congressional Democrats deep concerns.
“Our military are not trained as law enforcement officers,” Senator Elissa Slotkin, Democrat of Michigan and a former Pentagon official, said recently on ABC’s “This Week.” “But you’re coming right up to that line of logistics and support, and law enforcement.”
The deployments come even as the state of the border is fairly calm, with crossings having fallen sharply in recent months after the Biden administration took steps to limit migration.
The 4th Infantry Division is among the Pentagon’s most combat-ready units, reflecting Mr. Trump’s directive that it “prioritize the protection of the sovereignty and territorial integrity of the United States along our national borders.”
The Army in January alerted brigades from the 4th Infantry and the 82nd Airborne to prepare to deploy to the border. Each brigade has more than 3,000 soldiers, although it is unclear how many troops may actually be tapped for duty, Army officials said.
The headquarters personnel of the 10th Mountain Division, including its two-star commanding general, recently arrived in Fort Huachuca in Arizona to oversee the border operation.
Defense Department officials have left open the possibility that as many as 10,000 troops could deploy in the coming days. Marine Corps planners said they could be asked to supply 2,500 or more additional Marines.
Along with infantry, support troops specializing in supply, logistics, security and communications have already been sent to the border, the military’s Northern Command said in January.
The first two waves of active-duty troops were selected in part because they were ready to deploy on short notice. The first 500 Marines, for instance, were on standby at their base at Camp Pendleton in California to help support the firefighting efforts in Los Angeles.
