Iran's supreme leader said a "slap in the face" was delivered to the US, when the Islamic republic fired missiles at US troop bases in Iraq on Wednesday.
"Last night, a slap in the face was delivered," Ayatollah Ali Khamenei said in a speech broadcast live on state television.
His remarks came after he had vowed "severe revenge" for a US drone strike that killed Iranian military commander Qasem Soleimani near Baghdad international airport last week.
The next move appeared to lie with Washington.
A handout released by Iranian state TV shows rockets apparently launched from Iran against the US-held bases in Iraq. Source: IRIB (Iran state TV)
US President Donald Trump, who ordered the drone strike that killed Mr Soleimani, gave an initial response on Twitter: "All is well!".
Casualties and damage from the missile attacks were being assessed and Mr Trump said he would make a statement on Wednesday.
Mr Trump, who was impeached last month and faces an election this year, at the weekend threatened to target 52 Iranian sites if Iran retaliated for Mr Soleimani's killing.
Iranian state television said Iran had fired 15 ballistic missiles from its territory at US targets in its neighbour Iraq. The bases targeted were al-Asad air base and another facility in Erbil, the Pentagon said.
One source said early indications were of no US casualties, while other US officials declined to comment.
US paratroopers from the 82nd Airborne Division enter a C-130 transport plane at the al-Asad airbase, northwest of Baghdad in 2004. Source: Getty
Iranian television said 80 "American terrorists" had been killed and US helicopters and military equipment damaged. It provided no evidence of how it obtained that information.
Germany, Denmark, Norway and Poland said none of their troops in Iraq were hurt. Britain, which also has personnel in Iraq, condemned the Iranian action. Iraq said its forces did not suffer casualties.
More than 5,000 US troops remain in Iraq along with the other foreign forces in a coalition that has trained and backed Iraqi forces against the threat of IS militants.
"As we evaluate the situation and our response, we will take all necessary measures to protect and defend US personnel, partners, and allies in the region," Pentagon spokesman Jonathan Hoffman said.
President Donald Trump and first lady Melania Trump visited members of the military at Al Asad Air Base over the Christmas break. Source: AAP
In Tehran, Mr Khamenei said in a televised speech: "Military action like this is not sufficient. What is important is ending the corrupting presence of America in the region," renewing Tehran's long-standing demand for Washington to withdraw its forces.
Iranian Foreign Minister Mohammad Javad Zarif said the strikes "concluded" Tehran's response to the killing of Mr Soleimani, who had been responsible for building up Iran's network of proxy armies across the Middle East. He was buried in his hometown Kerman on Monday after days of national mourning.
"We do not seek escalation or war, but will defend ourselves against any aggression," he wrote on Twitter.
Iranian television reported an official in the supreme leader's office as saying the missile attacks were the "weakest" of several retaliation scenarios. It quoted another source saying Iran had lined up 100 other potential targets.
Analysts have said that despite its strident rhetoric, Iran will want to avoid any conventional military conflict with superior US forces. In the past, they say it has focussed on asymmetric strikes, such as sabotage or other military action via proxies.
US officials said Mr Soleimani was killed because of intelligence indicating forces under his command planned attacks on US targets in the region. They have not provided evidence.
Friction between Iran and the US rose after Mr Trump withdrew in 2018 from a nuclear deal between Iran and world powers, approved by his predecessor Barack Obama, and reimposed sanctions on Tehran slashing its vital oil exports.
Mr Khamenei, in his speech on Wednesday, ruled out any resumption of talks with Washington on the 2015 deal.
Mr Trump's US political rivals have challenged his decision to order Mr Soleimani's killing and questioned its timing in a US election year.
