Homeland Security Secretary Markwayne Mullin didn't back down from his threats to pull Customs and Border Protection officers from airports on Wednesday.

Watch in our video player above.

Mullin was asked about his threat to remove CBP officers from airports in cities that don't typically cooperate with federal immigration enforcement.

WATCH: Senate Democrats challenge Mullin over Homeland Security policies

Mullin said he isn't "punishing" places dubbed sanctuary cities by the Trump administration.

But he blamed those cities for "refusing to allow local and state enforcement officers to respond when we called" and said he needs to protect his staff. "If that means I gotta pull them out of Customs and Border Protection from processing international flights, I will," Mullin said.

Mullin did not say when he might implement his threat, which has sparked criticism from the travel industry for its potential to cause chaos just ahead of the World Cup.

GOP congressman tells DHS secretary to use more discretion in ICE arrests

In a rare example of a Republican criticizing the Trump administration's deportation program, Rep. Carlos Gimenez urged Mullin to put more emphasis on apprehending violent criminals.

"I think you need to use your discretion a little bit more as to who is being deported, who's being arrested, etc. Let's go after the worst of the worst," said Gimenez, whose South Florida district has a large heavy Cuban population.

Educate your inbox

Subscribe to Here’s the Deal, our politics newsletter for analysis you won’t find anywhere else.

Referring to a comment from Democratic Rep. Lou Correa, Gimenez said it's unacceptable that ICE recently failed to take six criminal suspects into custody in Orange County, California.

Mullin said ICE only has 48 hours after defendants are booked into local jails to take them into custody, a difficult deadline if not immediately informed of arrests.

"There's no excuse for it, but we just don't have the resources to get there like we need to," Mullin said.

Mullin says 'primary' border wall will be done in a year

Detailing progress on the wall the Trump administration is building separating the U.S. and Mexico, Mullin said the first layer — referred to as the "primary wall" — will be finished by "this time next year."

On some stretches of the border, Customs and Border Protection is building a secondary wall so that people trying to cross the border would have to go through two layers. That "secondary wall" will be finished by the summer of 2028, he said.

Homeland Security received $46 billion last summer from Congress to finish the wall along the border from San Diego to the Gulf of Mexico. Most of that will be protected by a physical wall, but CBP says 535 miles (860 kilometers) of remote, rugged border terrain will solely rely on detection technology.