Today President Donald Trump made good on his threat to go after "sanctuary cities" (cities that decline to investigate the immigration statuses of people within their jurisdiction) by going after their federal funds. He signed an executive order today attempting to implement a policy denying federal grants for any of these 200 estimated sanctuary cities if they refuse to assist the federal government in investigating immigration statuses.
One problem that was brought up in November after Trump's election: Law enforcement agencies and unions didn't support this mechanism of intimidating cities. It wasn't that they cared so much about the civil liberties. They were not going to support anything that prevented any sort of gravy train from rolling into their police stations. Law enforcement agencies are prime recipients of federal grants.
Trump, having run on a hard core law-and-order, stop-and-frisk, civil-rights-are-for-wusses campaign, was not interested in angering these guys. So his executive order today explicitly exempts grants "deemed necessary for law enforcement purposes."
Trump is also calling for the administration to publicize, on a weekly basis, a list of crimes committed by aliens "and any jurisdiction that ignored or otherwise failed to honor any detainers with respect to such aliens." One assumes these must be aliens the federal government detain or arrest after sanctuary city interactions. Otherwise there's a bit of a logic flaw in trying to highlight criminals who are illegal immigrants operating in cities that refuse to check their immigration status and report that information to the feds.
In any event, this executive action seems designed to maintain the loyalty of law enforcement agencies to Trump. Read the sanctuary cities section of the order below, check the full executive orders being signed today here, and check out this defense of sanctuary cities as a tool to encourage immigrants to cooperate with law enforcement to solve crime and keep communities safer: