I mean, if masked, unidentified people are kidnapping other people, what prevents _other_ masked, unidentified people to attack the kidnappers?
Where this goes, as I understand it from my European heritage, is that you are _already_ in a situation where there's a strong incentive for an active resistance force to appear.
ICE is clearly working as both an oppressive force, and as an incitement to violence. There have been precedents in history. It never ended well for _them_.
If you're referring to why a civilian milita isn't spinning to to stop them, that's because there are (basically) two groups of people in the US. The type that are strongly pro gun, pro militia, and have knowledge in both are generally actually supportive of this particular case, and furthermore wouldn't act anyway unless they or people they like were directly targeted. This is an unfortunate cultural aspect of the US, and correcting it would have a lag time of many decades. Furthermore, the groups that did attempt to correct it got crushed by the federal government for a few decades (see the MOVE bombings, and the Black Partners history), so are extra behind. However, spinning up a small militia for directly opposing this may happen. It would look similar to the CHAZ, but that requires a large group of dedicated and motivated people to spontaneously group together.
As for why law enforcement isn't taking sides, it's because doing so would basically be the start of a state succession attempt, and would bring federal agents in to take over the state. Some states have claimed they are willing to do that in certain situations (Alaska has said in the past it will use state troopers against government if they try to enact certain gun control laws), but no one is willing to go there yet. The best they can do now is categorically refuse to assist the feds.