A few days into his new job, newly appointed DHS Secretary Markwayne Mullin has already drawn major attention.

In his first major interview since confirmation, Mullin suggested he would consider pulling U.S. customs agents from airports in “sanctuary cities” unless local authorities agree to cooperate with Immigration and Customs Enforcement (ICE).

“Some of these cities have international airports — if they’re a sanctuary city, should they really be processing customs into their city?” Mullin told Fox News host Bret Baier​

“Seriously, 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 to focus on cities that want to work with us,” he continued.

Mullin’s plan would target major airline hubs, which also happen to be blue cities, including New York City’s JFK and LaGuardia, Newark, Boston, Philadelphia, Los Angeles, Chicago, San Francisco, Seattle, Denver, and New Orleans.

If those cities refuse to share data or grant access to ICE, he warned that federal customs officers could be removed from those airports. That move would effectively cut off most international travel to and from these cities, disrupting flights for millions of residents and visitors.

He argued that cities that will not help federal authorities keep the country safe should not receive the same benefits as those that do. The proposal would likely trigger immediate court challenges and could damage regional economies and global business ties.

By eliminating U.S. Customs and Border Protection (CBP) agents from sanctuary city airports, the Trump administration would be able to carryout it’s plan to terminate federal funding for jurisdictions that prevent local law officers (and jails) from working with ICE.

Last August, former Attorney General Pam Bondi sent a warning letter to 32 “sanctuary jurisdictions” threatening them to comply with federal law or face repercussions.