They literally wouldn't dare. They saw what happened last time, and now with Trump in office? They'd be lucky if the rubble of their cities didn't glow in the dark. Whatever you think of DJT, nobody wants to Press to Test.

Any of a variety of junior varsity fringe lunatic groups might try anything at any time, but it's been proven that they can't really cross the ocean and pull off big events in the US without state sponsorship. Not only will States not go there, they also actively impede anyone who might be associated with them from going there... Hezbollah, Hamas, etc could have conducted ops in the US, but Iran wouldn't allow that because they know the chickens would come home to roost. Iran's main guy got whacked because he was coordinating small-scale attacks on US service members in Iraq.