The Tenth Amendment reserves the "police power" to the States. Federal agents, like ICE, do not have the general power to enforce order and "preserve the peace" like police are supposedly for. That is why in the U.S. we do not have a national police force.
But the Trump Administration wants to pretend we do. So they have taken a relatively new agency, ICE (created in 2003), which has a narrow mandate of enforcing immigration law and enforcing customs (i.e. tariffs), and decided they are general purpose shock troops. In theory ICE officers don't have the authority to arrest protesters (at least not protesters who are U.S. citizens or lawful aliens) much less rough them up. If their job is disrupted by protests, they can call the local cops, like anyone else.
Which is why it is utterly absurd that ICE agents will provide security for the U.S. Olympic delegation. They are not a security service. The Trump administration really is trying to groom them to be their own all-purpose security brutes despite the fact that it has nothing to do with their legal mandate.
