Probably because they haven’t found sufficient evidence that those Muslim groups are conspiring to do so through force.
If they did have such evidence, I doubt there’s a U.S. Attorney in America who would look the other way. That’s the sort of prosecution that can make a career.
Or get your head sawed-off.
You’re kidding, right?
I’ve read about evidence right here on FR! No one touches the Muslims no matter what they do, plan or say. Or rarely.
Even Hassan slaughtered 14 people and wounded more than 2 dozen, and he was a lone misunderstood person! He was a one man jihadi with tons of Muslim extremist connections.
Your statement has no truth in it.
I would think there may be sufficient evidence (particularly in some terrorist groups within the US that have been linked to several major attacks that were successful), however the “relationships” that have been made with those groups MAY be valuable enough to preclude breaking it up. [I’m trying to be optimistic here because nothing else makes sense to me, frankly.]