The Nazis/socialists/fascists did: 60 million dead in WWII. If Europe keeps up its current course with the muzzies, it’ll get very, very ugly there again when they have a majority and nukes. With all the infiltrating and compromising we’re undergoing, we’ve got a much-worse-than-9/11 coming, too.
Look at what the Tsarnaev brothers did with a couple of homemade bombs.