ATLANTA (AP) — Federal immigration officers have been seen at an airport in Atlanta after President Donald Trump said he'd deploy agents to supplement the Transportation Security Administration during a government shutdown that has caused long lines at security checkpoints across the country.

On Monday morning, a handful of federal agents were seen by The Associated Press near busy lines at Hartsfield–Jackson Atlanta International Airport.

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Federal agents are a routine presence at international airports, where Customs and Border Protection officers screen arriving travelers and Homeland Security Investigations agents handle criminal cases tied to smuggling, trafficking and fraud.

What's unusual in the current moment is their visibility at TSA security checkpoints, a role typically handled by transportation security officers rather than federal investigators.

Hundreds of thousands of Homeland Security workers, including from the TSA, U.S. Secret Service and Coast Guard, have worked without pay since Congress failed to renew DHS funding last month.

Some fear the move to deploy federal immigration agents will only escalate tensions.

Trump said Sunday he would order federal immigration agents to airports to assist TSA by guarding exit lanes or checking passenger IDs unless Democrats agreed to fund the Department of Homeland Security. Funding for the department lapsed Feb. 14 as Democrats refused to fund Immigration and Customs Enforcement as well as Customs and Border Protection without changes to their operations in the wake of the deaths of Alex Pretti and Renee Good in Minneapolis.

Democrats are continuing to demand major changes to federal immigration operations — including policy changes that would require ICE agents to get a warrant from a judge before forcefully entering homes, the removal of masks and clear identifying information on uniforms.

Trump on Monday directed ICE officers not to wear face coverings in their work at airports. In a social media posted, Trump said he supports ICE officers wearing masks when dealing with "hardened criminals" but suggested it isn't necessary when assisting with the "MESS at the airports."

Grantham-Philips reported from New York. Associated Press writer Collin Binkley in Washington contributed to this report.