It’s about time. Finally, after multiple attacks on U.S. bases and allies, President Trump approved a military response against Iranian-allied militias in Iraq and Syria on the weekend. Mr. Trump has to be prepared to do more if the Iranians decide to escalate.

The Pentagon said U.S. F-15E fighters carried out the strikes on five targets occupied by Kataib Hezbollah, a Shiite militia allied with and armed by Iran. “Iran and their KH proxy forces must cease their attacks on U.S. and coalition forces, and respect Iraq’s sovereignty,...