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Two days after President Donald Trump tweeted that the United States has the “absolute legal right” to send detained migrants to sanctuary cites, he appeared to double down Monday, tweeting that they will be “given” to sanctuary cities, “subject to Homeland Security.”

Those Illegal Immigrants who can no longer be legally held (Congress must fix the laws and loopholes) will be, subject to Homeland Security, given to Sanctuary Cities and States! — Donald J. Trump (@realDonaldTrump) April 15, 2019

The Department of Homeland Security has not announced an official policy regarding the potential release of immigrant detainees in sanctuary cities and states, and officials with the agency have not responded to Mother Jones‘ request for comment.

DHS officials have said Border Patrol, Customs and Border Protection, and Immigration and Customs Enforcement are all overwhelmed by the influx of Central American migrants at the border and that there isn’t enough space to detain them. But in recent days, there have been reports of detention facilities operating well below capacity. The South Texas Family Residential Center in Dilley, Texas, for example, can hold up to 2,400 people, but as of early April, it held just 499, as KQED reported.

This push to send migrants to sanctuary jurisdictions appears to come as retaliation against cities and states that limit their cooperation with federal immigration authorities. It has been led by immigrant hardliners within the administration, particularly White House adviser Stephen Miller, and it comes amid turmoil in DHS leadership.

Historically, many migrants have settled in large cities like Los Angeles, Chicago, and New York, as well as border cities like Tucson and El Paso, which are known to have support networks and strong immigrant communities. As many immigrant advocates have argued, the administration would be busing or flying migrants to sanctuary cities that already receive many migrants.

Jenny Durkan, the Democratic mayor of Seattle, said in an op-ed Friday evening that “Seattle is not afraid of immigrants and refugees,” adding that the sanctuary city has always welcomed them.