Iran

There's been complaints about Congressmen advocating war with Iran. I find that silly. We've been at war with Iran for decades, or at least they've been at war with us. Taking embassy staff hostage is an act of war. So was sending troops into Iraq to kill ours a decade ago. And they're still chanting "Death to America!" So there's nothing new about this other than that we've been ignoring it. Given that Iran A. doesn't have much ability to hit us at home and B. would be an unpleasant place to invade, ignoring it is a valid strategic option.

Of course, adding nukes to Iran's existing overseas terrorist cells makes them much harder to ignore. Doing something about it would be much easier if we'd kept a residual force in Iraq instead of letting it disintegrate. Right now I don't see any good options.