Thousands of U.S. servicemen and servicewomen who  were deployed along the Mexico border will receive the Armed Forces Service Medal reserved for troops who “encounter no foreign armed opposition or imminent hostile action.”

“The Undersecretary of Defense has authorized the Armed Forces Service Medal to service members who have provided support to CBP, starting from April 7, 2018, [until a date to be determined],” said Army Lt. Col. Chris Mitchell, a Defense Department spokesman at the Pentagon.

Troops must have operated within 100 nautical miles—roughly 115 miles—from the Mexico border in Texas, New Mexico, Arizona, or California, according to the Marine Corps administrative message. Troops in San Antonio, Texas, and those serving in U.S. waters within 24 nautical miles of the coast are also eligible.

Thousands of service members have deployed to the U.S.-Mexico border since President Trump declared the porous border a crisis last year. Last month, the Pentagon approved the deployment of 2,100 troops to the border. The new troops will join 4,500 others.

The medal is approved only for operations “in which no other United States service medal is approved,” according to the Defense Department. It’s awarded to service members who, as a unit, participate in a U.S. military operation “deemed to be a significant activity and who encounter no foreign armed opposition or imminent hostile action.”

Service members have reportedly assisted with logistical support and aerial surveillance at ports of entry, and have provided Customs and Border Protection staff with support at temporary migrant holding facilities.

Meanwhile, Democratic lawmakers have ratcheted up criticisms of conditions at the border, assailing the treatment of migrants and refusing to provide additional funding for a border wall.