Iran has fired several ballistic missiles at a US military base in Qatar, less than two days after US bombers struck nuclear facilities in Iran.
There have been no reports of casualties.
Multiple news organisations reported that Iran gave both Qatar and the US advanced notice of the strikes.
US President Donald Trump took to Truth Social to express his "thanks" for Iran's early warning about the attack.
"Perhaps Iran can now proceed to Peace and Harmony in the Region, and I will enthusiastically encourage Israel to do the same," he said.
Mr Trump said while 13 Iranian missiles were "knocked down", one was "set free" because it was "headed in a non-threatening direction".
He appeared to suggest the US may not be looking to strike back.
"Most importantly, [Iran has] gotten it all out of their 'system'," he said.
"There will, hopefully, be no further HATE."
The US and UK warned their citizens in Qatar to shelter in place following a credible threat to the Al Udeid air base.
An ABC source in Doha reported hearing at least 20 booms.
Iran's security agency confirmed it had carried out a missile strike, firing as many missiles as had struck its nuclear sites on the weekend.
In a statement, advisor to the Qatari Prime Minister Majed Al Ansari said the missiles had been successfully intercepted.
He said the Qatari government condemned the strikes as a "flagrant violation" of the country's sovereignty and airspace, and of international law.
He said the Al Udeid base in Qatar, where an estimated 10,000 troops are usually stationed, had been evacuated earlier in the day, and that no-one was injured in the attack.
There have also been reports Iran targeted a US base in Iraq, but a US official told Reuters only the Qatar base was attacked.
Other sources told Reuters air defence systems were activated at the US Ain al-Asad airbase in Iraq for fear of a potential attack.
Multiple Gulf states close airspace
Qatar has just reopened its airspace, its Civil Aviation Authority said, after closing it minutes before Iran's attack.
Kuwait and Bahrain have also reopened their airspace after a "brief suspension", state news agencies reported.
Dubai airport also said "operations resumed after a brief suspension" but flights could see some delays or cancellations.
Emirates said it would continue flights as scheduled using flight paths well distanced from conflict areas.
Flight tracking sites showed many flights being diverted to other airports to avoid flying near Iranian airspace or over the Persian Gulf.
Further strikes on Iran
Iran's launches came at the same time a series of explosions were heard to the north of Tehran on Monday night.
An AFP journalist reported yellow flashes typical of Iranian air defences in the sky over Tehran shortly before 9pm local time.
Israel has been conducting continued strikes against Iranian targets in recent days.
In an earlier statement, Israel Defense Forces said 15 fighter jets conducted "extensive strikes" on Western Iran.
"The targets struck included underground military infrastructure, a missile storage site, and a UAV [Unmanned Aerial Vehicle] storage site belonging to the Iranian armed forces," the IDF said.
"In addition, earlier today, Israeli Air Force aircraft struck and neutralised missile launchers ready to launch toward Israeli territory in central Iran."
ABC/Reuters/AFP
