Why is it a game-changer? Because it marks the first time two Arab nations have teamed up to launch military operations against Islamists in a third. (The 2011 involvement of Saudi troops in putting down an Arab Spring uprising in Bahrain doesn’t count, because it wasn’t about Islamist terror, and because the Saudis were invited.) Even more important, it was the first time two Sunni Muslim nations struck radical Sunni groups in a third Sunni country.

That sets the precedent for the same countries—and others, besides—to join the fight against IS, in Iraq and Syria, as well as the campaign against al-Qaeda and its affiliates worldwide. Plenty of Sunni Arab nations have aerial firepower, much of it in the shape of American aircraft: Saudi Arabia, Kuwait, Qatar and Jordan all boast squadrons of F-16s or Apache gunships, or both.

If the UAE and Egypt can collaborate to can bomb Islamists in Tripoli, then the Sunni nations can do likewise in IS strongholds in Raqqa and Mosul. Of course, they might hesitate, especially before doing anything that helps Syria’s dictator, Bashar al-Assad. But the taboo on intervention has been lifted.