The head of U.S. Immigration and Customs Enforcement has threatened to “flood” Boston with immigration agents following Mayor Michelle Wu’s refusal to drop the city’s sanctuary policies.

Todd Lyons, the acting director of ICE, said during a Wednesday interview on "The Howie Carr Show," a conservative radio program, that the agency would expand its presence in the area. His comments followed a news conference on Tuesday at which Wu said that Boston would “not back down” from its policy of limiting police from cooperating with ICE on civil immigration enforcement efforts.

Lyons said that sanctuary policies like Boston's are detrimental to safety.

“We’re definitely going to, as you’ve heard the saying, flood the zone, especially in sanctuary jurisdictions,” Lyons said on the radio show. “Obviously Boston and Massachusetts decided that they wanted to stay sanctuary. … So 100%, you’re going to see more ICE presence.”

When asked about Lyons’ interview, Wu’s office directed NBC News to the mayor’s comments to reporters on the topic at an unrelated Thursday event.

“This is a beautiful, diverse, incredible city, and I have said it now very directly: This administration needs to stop attacking cities to hide their own failures,” Wu said.

Boston has a robust immigrant population, with more than 28% of its residents being foreign-born as of 2021. China, the Dominican Republic, Haiti and Vietnam make up the top countries of origin. In recent years, crime has continued to drop steadily, with homicides reaching a historic low by the end of 2024. Robberies, aggravated assaults and motor vehicle thefts and fraud related offenses have also dropped across Massachusetts, according to data released by the state.

Tensions between Wu and the Trump administration came to a head last week, when the Justice Department sent letters to 35 sanctuary jurisdictions demanding they end the immigration protections. The DOJ ordered the jurisdictions to submit plans by early this week to show that they are taking steps to ditch the policies, threatening to cut off federal funding and prosecute officials if the cities didn’t comply.

“You are hereby notified that your jurisdiction has been identified as one that engages in sanctuary policies and practices that thwart federal immigration enforcement to the detriment of the interests of the United States,” the letter, signed by Attorney General Pam Bondi, said. “This ends now.”

Wu hit back in a heated letter to Bondi on Tuesday, calling the attorney general’s demands an “attack” on U.S. cities and a tactic to “make Americans fearful of one another.”

“On behalf of the people of Boston, and in solidarity with the cities and communities targeted by this federal administration for our refusal to bow down to unconstitutional threats and unlawful coercion, we affirm our support for each other and for our democracy,” Wu wrote. “Boston will never back down from being a beacon of freedom, and a home for everyone.”

The Boston mayor further slammed the DOJ’s demands during a news conference outside City Hall that same day.

“You are wrong on the law and you are wrong on safety,” Wu said. “Most of all, you are wrong on cities.”

Boston’s immigration protections stretch back to 2014, when the city enacted the Boston Trust Act aimed at promoting trust between immigrant communities and local law enforcement. The legislation, which was amended in 2019, allows the Boston Police Department to collaborate with ICE on issues of “significant public safety” — including human trafficking, child exploitation, drug and weapons trafficking and cybercrimes — but keeps the department out of civil immigration enforcement. Most recently, at the end of 2024, the City Council adopted a resolution that reaffirmed the act.

“The Trust Act’s provisions have been instrumental in fostering a safe and welcoming environment for all residents, ensuring that immigrants can engage with local law enforcement without fear of deportation,” the resolution said.