In a sharp escalation of border security efforts, U.S. and Mexican forces will soon begin synchronized patrols along their respective sides of the southern border, the Pentagon announced Wednesday.

The joint effort underscores the Trump administration’s push to have an aggressive posture on the border, a part of a key campaign promise President Donald Trump made to dramatically curtail illegal immigration.

One of Trump’s first moves after taking office in January was surging some 3,600 American troops across the U.S.-Mexico border, with the Army’s 10th Mountain Division serving as the headquarters element overseeing much of the mission. The surge in active-duty troops is in addition to some 2,500 National Guard members who had already been deployed there before Trump took office.

Read Next: USS Truman Commander Fired After Collision with Merchant Ship near Suez Canal

Following a meeting between Gen. Gregory Guillot, head of U.S. Northern Command and the top American official overseeing troops in the region, and Gen. Ricardo Trevilla Trejo, the top officer of Mexico’s military, a Pentagon statement said that the pair agreed to “increase information sharing and establish methods for immediate communications.”

“Border security is national security; we’re going to get 100% operational control of our southern border,” Defense Secretary Pete Hegseth said during an address to Pentagon staff earlier this month. “That will be a focus of this department.”

Yet, as the troop presence grows, the Pentagon has provided scant details on the exact scope of the mission. Media access remains restricted — a sharp contrast to the often open coverage granted during previous military operations in Iraq and Afghanistan.

The lack of clarity has fueled questions about whether troops will directly engage with migrants or contribute to physical barrier construction. Air Force personnel on the mission have also removed name tapes and unit identifiers during flights with migrants, the only service to do so.

Also, National Guardsmen who have served on the border in recent years have reported issues with their units not being utilized during the missions.

Other major deployments include military police units from most major Army installations in the U.S., including Fort Cavazos, Texas; Fort Carson, Colorado; and Fort Drum, New York.

The military has also deployed Marine detachments from the 1st Combat Engineer Battalion, 1st Marine Division, and 7th Engineer Support Battalion, 1st Marine Logistics Group, both out of Camp Pendleton, California.

Related: Air Force Has Troops Remove Names, Unit Patches from Uniforms During Deportation Flights

Story Continues