One of the Middle East’s oldest conflicts has entered a new era

EVENan ineffective act can be transformative. The Middle East spent the first half of this month waiting for Iran to retaliate for , on April 1st, which killed two generals at its embassy compound in Damascus. When it came, on the night of April 13th, it was bolder than expected, a barrage of more than 300 missiles and drones aimed at Israel. That it caused no death and little destruction did not diminish its import: this was the first time Iran has struck Israel directly.Now the region waits nervously again, this time to see when and how Israel conducts its almost inevitable response. Its partners in the West, particularly America, must strike a delicate balance between defending their ally and restraining it. Friendly Arab states are in an awkward position, too. And the belligerents themselves, Iran and Israel, must now navigate a conflict in which the old rules of engagement have been abruptly shredded.