ICE Agents. He mentions the Constitution and the Courts, but those are a dead end for States and Cities when it comes to federal laws. For reference see how California Gov. Newsome's lawsuit fared in Federal Court yesterday.
Mayor Brandon Johnson warns Trump that Chicago has 'to go as far as necessary’ to protect the Constitution
https://www.wbez.org/immigration/2025/06/17/mayor-brandon-johnson-warns-trump-that-chicago-has-to-go-as-far-necessary-to-protect-the-constitution