Four states have deployed National Guard troops to the U.S.-Mexico border, answering a call to action from President Donald Trump.

The commitment so far totals more than 1,500 troops to meet a demand of 2,000 to 4,000 from the White House.

Texas will deploy 1,000 National Guard members to the border, Gov. Greg Abbott announced, beginning with about 300 right away. “We may be in this for the long haul,” he said in a radio interview. The state already had 100 Guard members working on the border with law enforcement before Trump ordered increased security in an April 4 memorandum to his attorney general and the Departments of Defense and Homeland Security.

The Arizona National Guard is sending about 338 members to the U.S.-Mexico border, Gov. Doug Ducey announced. "The Guard will provide air support, reconnaissance support, operational support, construction of border infrastructure and logistical support,” an Arizona National Guard statement said.

The New Mexico National Guard is sending 250, pledged Gov. Susana Martinez. Coordination was underway to make certain the Guard members called up for duty were not local law enforcement officers.

California is considering deploying some of its National Guard force as well.

South Carolina, which doesn’t have a border with Mexico, is sending National Guard troops to help Texas, Abbott said. Details were not announced.