First reported by Military Times, U.S. Northern Command revealed on Tuesday which units are currently deployed to the U.S.- Mexico border in support of the U.S Department of Homeland Security. The active-duty units were deployed last fall in response to large caravans making their way through Central America and towards the American border.

Many of the units deployed to the border are engineers, military police, and transportation units. From the updated list that was released in November, a major difference is the increase in Marine Corps units.

At the start of March, an increase of 1,000 active-duty troops were deployed to the border, bringing the total number to 6,000.

“To clarify, the composition of the more than 5,000 personnel currently on the Southwest Border (and growing to approximately 6,000 by March 1) is comprised of both Active Duty and National Guard personnel,” the Pentagon said in a statement. “Specifically, approximately 2,100 personnel are National Guard and the rest are Active Duty.”