“They don’t invade with an army, air force, and navy.”
ISIS has an “army” of fighters. Air force or navy - give them the opportunity, weapons and the funding, they’ll have that, too.
They do not have forces that can invade the US. Their only weapon here is terror. Unless we toss the Muslims out of our country, we will always be at risk. Let them kill each other over there. Keep them out of civilized countries.