As Iran retaliates, largest US military base in Middle East hit by ballistic missile, Qatar says

Secretary of State Marco Rubio said Monday that knowledge of pending Israeli action played a part in the decision to strike Iran now -- though denied that Israel forced the U.S.' hand.

"It was abundantly clear that if Iran came under attack by anyone -- the United States or Israel or anyone -- they were going to respond, and respond against the United States. The orders had been delegated down to the field commanders," Rubio told reporters before his briefing for members of the Gang of 8 on Capitol Hill.

Rubio said the near-immediate retaliation from Iran had proven his point -- saying missiles had been "prepositioned" to strike before the initial attack on the leadership compound.

"If we stood and waited for that attack to come first, before we hit them, we would suffer much higher casualties," Rubio said. "We knew that there was going to be an Israeli action. We knew that that would precipitate an attack against American forces, and we knew that if we didn't preemptively go after them before they launched those attacks, we would suffer higher casualties."

When asked if the U.S. was forced to strike because of an impending Israeli action, Rubio said no, and that U.S. military action would have eventually been necessary anyway.

Asked about regime change, Rubio said it was not a chief objective of the operation, but that "we would not be heartbroken" if it happened.

Pressed on whether the U.S. would play a role in shaping the next government of Iran, Rubio was noncommittal.

"I mean, we might. We'll see how circumstances play out," he said.

-ABC News' Shannon K. Kingston

All personnel at the U.S. embassy compound in Amman, Jordan, have "temporarily departed" due to an unnamed threat, according to a brief security alert.

The embassy had previously issued a shelter-in-place order for all mission personnel, telling them to avoid the embassy compound "as it may be targeted."

The U.S. struck more than 1,250 targets in Iran during the first two days of "Operation Epic Fury," according to U.S. Central Command.

Among the targets, 11 Iranian ships have been destroyed, CENTCOM said.

"Two days ago, the Iranian regime had 11 ships in the Gulf of Oman, today they have ZERO," CENTCOM said in a post on X while releasing an unclassified video of a strike. "The Iranian regime has harassed and attacked international shipping in the Gulf of Oman for decades. Those days are over."

Qatari air forces shot down two aircraft they claim were coming from Iran, the Qatari Ministry of Defense said Monday.

"The Ministry further emphasizes the Qatar Armed Forces possess full capabilities and resources to safeguard the state's sovereignty and lands, and to respond firmly to any external threat," the Qatari Defense Ministry said in a statement.

There are U.S. military assets in Qatar.

-ABC News' Kirit Radia