U.S. President Joe Biden returned to Washington on Saturday to consult with his national security team as Iran launched a retaliatory drone and missile attack on Israel.

Biden cut his weekend trip to Delaware short to monitor developments and meet with Cabinet members and other top U.S. officials, the White House said.

Iran on Saturday launched dozens of drones at Israel that will take hours to reach their targets, Israel’s military said, an attack that may trigger a major escalation between the regional archenemies, with the United States pledging to back Israel.

“President Biden has been clear: our support for Israel’s security is ironclad. The United States will stand with the people of Israel and support their defense against these threats from Iran,” White House National Security Council spokesperson Adrienne Watson said in a statement after the Iran attack began.

Biden was being regularly updated on the airborne attack and planned to meet with his national security team in the White House, she said.

Tehran has vowed to retaliate for Israel’s attack on Iran’s embassy compound last week in Damascus that killed a senior commander in the Iranian Revolutionary Guard Corps’ overseas Quds Force and six other officers.

Earlier on Saturday, U.S. Defense Secretary Lloyd Austin spoke with Israeli Defense Minister Yoav Gallant to discuss “urgent regional threats,” the Pentagon said, and reiterated full U.S. support for Israel against attacks by Iran and its proxies.

Jake Sullivan, Biden‘s national security adviser, relayed a similar message of U.S. support to his own Israeli counterpart, Tzachi Hanegbi, he said in a post on X.

Israel subsequently put its military on full alert and canceled all educational and other youth activities.

On Friday, Biden warned Iran against retaliation even while predicting the attack may be imminent. “We are devoted to the defense of Israel. We will support Israel. We will help defend Israel and Iran will not succeed,” he said.