Immigration officers have been seen at several airports across the United States after being deployed by President Trump to help alleviate long lines and severe delays caused by understaffing at security checkpoints.

Trump said Saturday that he would reassign agents from Immigration and Customs Enforcement to support the Transportation Security Administration. The TSA has been critically short-staffed over the past week as thousands of its security officers, who have been working without pay since the Department of Homeland Security’s funding lapsed five weeks ago, have been calling out of work in increasing numbers.

Those shortages have resulted in extraordinarily long lines at a number of major airports in the U.S., with some travelers reportedly waiting as long as six hours to get through security. With few signs of progress toward a deal to reopen DHS, the Trump administration has tapped in the agency at the center of its controversial immigration crackdown in hopes that its officers will help ease the problem.

The TSA is one of many agencies inside the Department of Homeland Security. The DHS has been shut down for the past month because of an ongoing funding fight over reforms to the Trump administration’s immigration policy. Even though the disagreement has nothing to do with the TSA, its employees are still affected because the DHS as a whole doesn’t have money to cover payroll.

TSA employees were still receiving their paychecks on time for the work they did before DHS funding lapsed. They got a full paycheck a few days after the shutdown started and a partial check in early March. Last Friday was their first scheduled payday, when they received nothing. Callouts subsequently surged.