Even if they are Hamas what consequences would that entail? Hamas has no real power in the US and everything they care about exists in Palestine.
Would they organize terrorists attacks in the US? It’s not impossible but I think it’s much more likely that they’d use the safety and security of living in the US (ya know, a secular, pluralistic democracy–the opposite of what they want for Palestine) to merely coordinate things with their allies in Gaza.
Every extremist religious organization that’s ever come to the US ends up with a very rude awakening when the second or third generation ends up not believing in their religion anymore. Secular rule and freedom of religion (and from religion) are just too powerful for extremists to overcome when they’re not isolated from the rest of society.
As long as any extremists can’t build isolated communities of co-believers they’ll never make headway in places like the US. Their children will get exposed to too much diversity of cultures and beliefs. It’s highly unlikely that they will be able to avoid the inescapable march of atheism taking over the West.
BTW: If you are part of a strongly religious society. Say, the type that forces women to dress a certain way or treats non-adherents as lesser human beings then congratulations! You are promoting atheism.