A military response from Israel is now expected, although it was unclear how robust it would be. It could take several hours for the drones to reach their intended targets, the identity of which is still unclear. Attacks from Iranian soil to Israel proper would represent a major escalation in regional warfare.

President Biden cut short his weekend in Delaware and rushed back to the White House, where he was joined by a team of national security advisors who had been bracing for violent reprisal after April 1 airstrikes blamed on Israel killed seven senior Iranian officials at an Iranian diplomatic mission in Syria.

Rear Adm. Daniel Hagari, a spokesman for the Israel Defense Force, reported the launch of Iranian drones and said Israel was already on high security alert, canceling school and large public gatherings until further notice.

“Iran has begun an airborne attack against Israel,” White House national security spokeswoman Adrienne Watson said.

Direct Israel-Iran military actions would be a game-changer, U.S. officials said.

“We are in totally uncharted territory,” Mairav Zonszein, Middle East analyst with the International Crisis Group, said on X, the platform formerly known as Twitter.

Biden administration officials, along with counterparts from several Arab and European nations, in recent days had been urging Iran to show restraint even as Tehran’s heated rhetoric rose and preparations for an attack were clearly underway.

U.S. officials also urged Israel to calibrate any response commensurate with Iran’s action.

But a wider conflict, in a region already reeling from Israel’s devastating war in Gaza, will further stymie Washington’s diplomatic efforts aimed at easing tension and freeing hostages held by the Hamas militant group, including several U.S. citizens.

It could also undermine Biden’s domestic support from war-weary voters just under seven months ahead of the U.S. presidential election.