One of the (many) insane things that our government does is to allow into our country a bunch of “shady” characters. Then they “watch” them to see if they’re behaving badly. And then they inevitably lose track of them. And then the “shady” characters do something bad. Then the government twists itself into knots trying to determine their “motives” and rather their bad behavior was an “act of terrorism”. I think a sane government wouldn’t allow the “shady” characters into our country to start with. But maybe it’s me that’s insane.
The feds knew about the Boston Bomber and did nothing. They even let him come back into the US when his passport expired. They knew about the 911 freaks and did nothing. It’s a good bet more than half the student visas today have expired and nothing is being done. Sending them packing would be a start. Tip of the iceberg.