Cities are not beholden to carry out federal immigration law. If the federal government wants to send ICE agents, then that's the federal government's job. Cities have so much to worry about, and where are they going to get the funds to address this additional concern if the government wants them to address immigration issues? Furthermore, I think it's up to each city how they want to determine how to interact with local immigrant and refugee populations. A one size fits all answer doesn't work for this situation, and it will only serve to rip families apart.