No one was injured, according to the Qatari Ministry of Defense.
President Donald Trump announced "major combat operations" against Iran on Saturday, with daytime strikes in the joint U.S.-Israel attack targeting military and government sites, officials said.
On Sunday, Iranian state television confirmed that Ayatollah Ali Khamenei was among those killed by airstrikes in Tehran on Saturday.
Iran is responding to the U.S.-Israeli operation with missile and drone attacks targeting Israel, regional U.S. bases and Gulf nations. American diplomatic facilities have also been attacked.
In Lebanon, Israel is intensifying its long-running strike campaign against the Iranian-aligned Hezbollah militia.
Watch special coverage on Nightline, "War with Iran," each night on ABC and streaming on Disney+ and Hulu.
The State Department is urging Americans to leave 14 countries in the Middle East immediately "due to serious safety risks," Assistant Secretary Mora Namdar said on X.
Before heading into a briefing for members of the Gang of 8 on Capitol Hill, Secretary of State Marco Rubio told reporters that "the hardest hits are yet to come from the U.S. military."
"The next phase will be even more punishing on Iran than it is right now," he said.
Rubio said that he did not know how long the hostilities could last.
"We have objectives. We will do this as long as it takes to meet those objectives," he said.
-ABC News' Shannon K. Kingston
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."
