Well they might at the start, but it's as simple as making an example of them. As soon as they fear consequences, it ends. Only the real hardline Ukrainians would persist. These people were too cowardly to go fight for Ukraine, so why would they have the courage to fight the state?
They might not fight for Ukraine.... But they might fight to get rid of the POTUS.
There is quite a handful of mentally unstable far left groups in North America at the moment. But that being said , they probably exposed themselves on Reddit or 4Chan before it happens.