Mullin weighs using airport customs as leverage against sanctuary cities

Such a move could effectively lock out global travelers from major cities like New York, New Orleans and Philadelphia, placing a damper on incoming commerce and economic benefits that could directly affect those cities' business environments and tax bases.

Mullin told "Special Report" that as sanctuary cities refuse to cooperate with DHS to enforce immigration law, the agency may need to consider that when providing services to those cities.

"This one area we may take a look at is some of these cities have international airports," he said. "If they're a sanctuary city, should they really be processing customs into their city?"

Many sanctuary cities did not respond to requests for comment, even as Mullin said such jurisdictions are on their face "not lawful" and should not consider themselves absolved of certain federal policies.

International airports and their customs apparatus present a potential leverage point, given that DHS controls them and oversees enforcement agencies like ICE, CBP and USCIS that sanctuary cities oppose and hinder.

As of late Wednesday afternoon, none had provided comment.

In his interview, Mullin said that the subject needs to be given serious consideration.

"If they're a sanctuary city, and they're receiving international flights, and we're asking them to partner with us at the airport, but once they walk out of the airport they're not going to enforce immigration policy, maybe we need to have a really hard look at that because we need a focus on cities that want to work with us," he said.

Fox News Digital's Nora Moriarty contributed to this report.