More than 80 US forces have reportedly been killed during Iranian missile strikes to intended US military bases in Iraq on Wednesday, IRIB quoted a source close to Iran's Revolutionary Guards (IRGC).
"According to the accurate reports of our sources in the field, at least 80 American troops were killed and some 200 others were wounded, who were immediately transferred out of the airbase by helicopters," said an informed source at the Islamic Revolution Guards Corps.
"Ain al-Assad airbase was a strategic site for the US which was used to support drones," Tehran Times reported quoting the source.
As many as 20 critical points of the base were hit by 15 missiles and a significant number of UAVs and helicopters were destroyed, source added.
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"Despite the fact that Americans had been on high alert, their air defense was unable to respond."
"As many as 104 critical US-held points in the region have been targeted, which would be attacked upon the US's first mistake," the source added further.
The Islamic Revolution Guards Corps targeted the US airbase of Ain al-Assad in Anbar province in western Iraq after launching a wave of attacks in early hours of Wednesday to retaliate the US assassination of IRGC Quds Force commander, Lt Gen Qasem Soleimani.
Iran's Revolutionary Guards confirmed that they fired the rockets in retaliation for last week's killing of Qassem Soleimani, according to state TV.
"We are working on initial battle damage assessments," Pentagon spokesman Jonathan Hoffman said in a statement, adding that the bases targeted were al-Asad air base and another in Erbil, Iraq.
US President Donald Trump has been briefed on reports of the attack and was monitoring the situation, White House spokeswoman Stephanie Grisham said.
"We are aware of the reports of attacks on US facilities in Iraq. The president has been briefed and is monitoring the situation closely and consulting with his national security team," Grisham said in a statement.
Earlier on Tuesday, US Defense Secretary Mark Esper said the United States should anticipate retaliation from Iran over the killing in Iraq of Soleimani, commander of the elite Quds Force.
"I think we should expect that they will retaliate in some way, shape or form," Esper told a news briefing at the Pentagon, adding that such retaliation could be through Iran-backed proxy groups outside of Iran or "by their own hand."
"We're prepared for any contingency. And then we will respond appropriately to whatever they do."
Stock markets in Asia fell sharply on news of the rocket attack, while investor safe havens including the Japanese yen and gold shot higher.
Soleimani, a pivotal figure in orchestrating Iran's long-standing campaign to drive US forces out of Iraq, was also responsible for building up Tehran's network of proxy armies across the Middle East.
He was a national hero to many Iranians, whether supporters of the clerical leadership or not, but viewed as a dangerous villain by Western governments opposed to Iran's arc of influence running across the Levant and into the Gulf region.
"We Will Take Revenge"
A senior Iranian official said on Tuesday that Tehran was considering several scenarios to avenge Soleimani's death. Other senior figures have said the Islamic Republic would match the scale of the killing when it responds, but that it would choose the time and place.
"We will take revenge, a hard and definitive revenge," the head of Iran's Revolutionary Guards, General Hossein Salami, told the throngs in Kerman, Soleimani's hometown in southeastern Iran.
Soleimani's burial went ahead after several hours of delay following a stampede that killed at least 56 people and injured more than 210, according an emergency official quoted by Iran's semi-official Fars news agency.
Soleimani's body had been taken to holy Shi'ite Muslim cities in Iraq and Iran, as well as the Iranian capital, Tehran, before arriving for burial in the city cemetery's "martyrs section", according to the semi-official news agency ISNA.
In each place, huge numbers of people filled thoroughfares, chanting: "Death to America" and weeping with emotion. Supreme Leader Ayatollah Ali Khamenei wept as he led prayers in Tehran.
Prompted by the strong public backlash over Soleimani's killing on Iraqi soil, lawmakers in Iraq voted on Sunday to demand a removal of all foreign forces from the country.
More than 5,000 US troops remain in the country along with other foreign forces as part of a coalition that has trained and backed up Iraqi security forces against the threat of Islamic State militants.
US officials have said Soleimani was killed because of solid intelligence indicating forces under his command planned attacks on US targets in the region, although they have provided no evidence.
Ali Shamkhani, secretary of Iran's Supreme National Security Council, said 13 "revenge scenarios" were being considered, Fars news agency reported. Even the weakest option would prove "a historic nightmare for the Americans", he said.