WATCH: Former ICE director reveals what goes into agency’s decisions on cities to target

While some Democrats have accused the Trump administration of politically targeting Democratic cities for enforcement, former acting U.S. Immigration and Customs Enforcement Director John Sandweg shared insight about how the agency selects the next city for operations.

Sandweg, who served as acting ICE director under President Barack Obama from 2013 to 2014, told Fox News Digital during an interview that the existence of sanctuary policies harboring illegal aliens does play a major role in determining cities for targeting. However, Sandweg said that this is not for purely political reasons.

"The biggest driver would be immigrant population, how significant a population is there in that particular community. And then the second thing is, is there something like a sanctuary policy that would increase the number of at-large targets, meaning people who ICE wants to take into custody who are not currently in a prison or jail," he explained. "Those are the traditional factors that ICE would rely on in making determinations about where to do at-large surges."

In 2025, the Trump administration surged ICE agents to cities like Minneapolis, Los Angeles, Portland and Chicago. All of these were major cities with significant immigrant populations, and all had sanctuary policies. Sandweg said that he expects crackdowns such as these to be "just beginning."

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"You want to go where the criminals are … and so, you're going to be looking at data about where is it that we can find the biggest bang for our buck," he explained, adding, "Traditionally, that's going to be in larger urban cities, just because they're higher density population, and you're more likely to find your criminal populations there."

When it comes to the role of sanctuary cities in ICE’s targeting process, Sandweg said that "sanctuary policies are not all equal."

"ICE is really good at getting people in prisons and jails. There isn't a person booked into a prison or jail in the United States today that ICE doesn't get visibility on," he explained. "While we're paying a lot of attention to these kinds of very public standoffs between protesters and DHS agents in Minneapolis and other places, there's a lot going on behind the scenes the public doesn't understand, including the picking up of people in prisons and jails, federal, state, local, across the country."

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Though he said that some sanctuary jurisdictions are willing to cooperate with ICE in arresting illegals with serious criminal charges, such as violent crimes, there are some that are not willing to do that. 

Sanctuary jurisdictions that refuse to honor requests by ICE to hold illegal aliens, called "detainers," present their own operational challenge, said Sandweg. This, in turn, can potentially lead to the agency deciding to surge more agents and resources to the area.

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"There are jurisdictions … that have very restrictive sanctuary policies, where you're sitting there scratching your head saying, these are bad guys, why won't they give us custody of this person in jail?" he said. "In those jurisdictions, you're going to find more targets because those people, ICE normally would take custody of them in jail or prison."