terrorist attacks

Yes, we have terrorist attacks in the US. The most famous one is September 11th, 2001. Some other attacks were school shootings(very angry students or people) and bombings(disgruntled people). Some of these attacks don't have a real motive, it may be that the "terrorist(in this case the person harming others)" is in emotional turmoil and is trying to solve their problems by killing other people and then themselves. Other attacks may be out of anger at someone or something and this is their revenge. And still other attacks are the actually defined terrorist attacks are caused by people who want to kill us all, burn our country to the ground, and throw the ashes into the sea. The US prevents terrorist attacks by not allowing any sharp objects onto planes(knitting needles are the only exception), not allowing more than 4 ounces of any liquid onto planes, not allowing guns, ammo, or fireworks(combustibles) onto planes, and everything is scanned before going onto planes. Some attacks can't be prevented by these means, but only with careful observation(psychiatric) or by learning about them before it is going to happen.