The Houthis of Yemen think they’re at war with the West. With the news that three undersea fiber-optic cables were severed off the Yemeni coast and that one of their ballistic missiles took lives for the first time upon striking a container ship, it’s time to acknowledge that we are at war with them.

The much harder question is how to fight this kind of asymmetric foe.

What the Houthis are proving is that the developed West faces rising challenges on two fronts from weaker enemies, ranging from nonstate actors to the likes of Iran and Russia. And for all the still-extraordinary power of U.S. carrier fleets, the answer to those challenges can’t always boil down to just getting tougher, drawing lines and establishing deterrence — the standard Washington strategy.