It's interesting that the shooter in Frankfurt yesterday was a guy from Kosovo. One would think that he would have a soft spot for the US Air Force for their ousting of the Serbs from his country over a decade ago.
However, that is sooooo 90s, and we're in the 10s. Also, infidels are still infidels, even if they are former allies. Osama was happy to take US help in ousting the Russians from Afghanistan, then turned around and aimed at the less-egregious infidels.
Be thankful that modern Christian history is short on jihad-style thought; otherwise, we'd have the Westboro folks shooting at mourners rather than damning them loudly. Unfortunately, they're allowed to do that thanks to the First Amendment. They're allowed to question one's eternal destination as long as they don't try to expedite one's trip to eternity.