ISIS claims that they were involved. Not too weird, right, because they don't care about lying, do they? Except that, historically, they have not made such false claims before...well, maybe they're getting desperate...except it does seem like there are a few things that might lend some credibility to the claim. They've also doubled down and said it's not a false claim, for whatever the he'll that's worth. I think, one way or the other, there's just going to be a lot of conspiracy theory stuff over this one.