US President Donald Trump ordered an airstrike at Baghdad International Airport that killed Qasem Soleimani, a key Iranian military commander, in a "decisive defensive action to protect US personnel abroad" that was intended to deter "future Iranian attack plans," the Pentagon confirmed Thursday.
Soleimani -- the head of Iran's Islamic Revolutionary Guards Corps (IRGC) Quds Force unit -- and Abu Mahdi al-Muhandis -- the deputy head of the Iran-backed Iraqi Popular Mobilization Forces (PMF) -- were among those killed in the attack early Friday morning local time, according to a statement from the PMF, which said the pair "were martyred by an American strike."
The assassination of the top military leader marks a major escalation in regional tensions that have pitted Tehran against the US and Washington's Gulf Arab allies in the region.
Soleimani was revered in Iran, where three days of national mourning have been declared. In a message published to his official website, the country's Supreme Leader, Ayatollah Ali Khamenei, vowed revenge for the killing, saying that "harsh revenge awaits the criminals" involved.
Formed in 2014 to fight ISIS, the PMF is a Shia paramilitary force made up of former militias with close ties to Iran. It was recognized under a 2016 Iraqi law as an independent military force that answers directly to the prime minister.
Soleimani and his Quds Force were responsible for the deaths of hundreds of American and coalition service members, and the wounding of thousands more, the Pentagon added. The Pentagon also blamed the Iranian general for orchestrating attacks on coalition bases in Iraq in recent months, including an attack on December 27 that culminated in the deaths of an American contractor and Iraqi personnel.
Khamenei warned the fight would continue -- and added it had been Soleimani's wish for years to become a martyr.
"His pure blood was shed in the hands of the most depraved of human beings," Khamenei said.
In a tweet, Iran's Foreign Minister, Javad Zarif, described the US strike as an "act of international terrorism," adding that it was an "extremely dangerous and foolish escalation" and that "the US bears responsibility for all consequences of its rogue adventurism."
In a statement, Muqtada al-Sadr, who leads the largest political bloc in Iraq's parliament, has ordered the revival of the "Mahdi Army," which fought US troops during the 2003 invasion. He also called on Iraqis to exercise "wisdom and shrewdness."
One pro-Iranian Iraqi cleric, Qais al-Khazali, called for the removal of US forces from Iraq and for the "demise" of Israel, as a response to the deaths of Soleimani and Muhandis.
Hassan Nasrallah, head of the Iran-backed Lebanese militant and political group Hezbollah, has also vowed to avenge the assassinations.
Iraqi Prime Minister Adil Abdul Mahdi said he considered the assassination of Muhandis an "attack on the Iraqi state, government and people," according to a tweet by Abdul Mahdi's media office.
'Target of opportunity'
It also comes just hours after the Pentagon issued a strong warning to Iran-backed militias amid concerns they may conduct further provocations against the US following their attempt to storm the US embassy in Baghdad. According to the Pentagon, Soleimani also approved that attack.
Soleimani was "actively developing plans to attack American diplomats and service members in Iraq and throughout the region," according to the Pentagon, which cited the threat to US lives as justification for killing one of Iran's top-ranking military officials.
But a US official told CNN the strike against Soleimani was a "target of opportunity."
The strike had presidential authorization and the US opted for a pre-emptive option after the previous moves of maximum pressure didn't change the Iranian pattern of behavior, the official said.
The Green Zone in Baghdad was completely locked down by Iraqi security forces to prevent any emergency following the strike, two Iraqi security sources told CNN.
Feisal Istrabadi, the founding director of the Indiana University Center for the Study of the Middle East, told CNN that the Iraqi government would be considerably weakened by the fact the strike happened on its soil.
"There will be an opportunity for the destabilization of the country," he said. "This is a huge deal throughout the Middle East. The fact that it was done over the territory of Iraq means that Iraq will become what I feared it would become from the beginning: the battleground between Iran and the United States."
Biden says US strike 'dynamite in a tinderbox'
In the US, the news of Soleimani's killing generated starkly different reactions along party lines, with Republicans heaping praise on Trump and Democrats expressing concerns about the legality and consequences of the strike.
Former Vice President Joe Biden, a frontrunner in the Democratic presidential race, warned that the US strike could trigger a conflict across the Middle East and that Iran will almost certainly retaliate with attacks of its own.
"President Trump just tossed a stick of dynamite into a tinderbox, and he owes the American people an explanation of the strategy and plan to keep safe our troops and embassy personnel, our people and our interests, both here at home and abroad, and our partners throughout the region and beyond," Biden tweeted.
Democratic Sen. Chris Murphy of Connecticut emphasized that Soleimani "was an enemy of the United States" in a tweet, but asked: "The question is this -- as reports suggest, did America just assassinate, without any congressional authorization, the second most powerful person in Iran, knowingly setting off a potential massive regional war?"
In a more explicit statement, Sen. Tom Udall of New Mexico said, "President Trump is bringing our nation to the brink of an illegal war with Iran without any congressional approval as required under the Constitution of the United States."
Some key members of Congress -- such as Senate Minority Leader Chuck Schumer, a New York Democrat who is a member of the congressional Gang of Eight leaders, who are briefed on classified matters -- had not been made aware of the attack ahead of time. It's not clear how many other lawmakers had advance notice of the strike.
Republicans reacted with almost uniform praise for Trump.
"I appreciate President @realDonaldTrump's bold action against Iranian aggression," GOP Sen. Lindsey Graham of South Carolina, a fierce Trump ally, wrote in a tweet Thursday. "To the Iranian government: if you want more, you will get more."
Two sources tell CNN that key Senate staff on relevant committees on national security and appropriations, along with leadership staff, will be briefed Friday afternoon in a classified setting by administration officials.
Sen. Ben Sasse, Republican of Nebraska, said in a news release that "General Soleimani is dead because he was an evil bastard who murdered Americans" and "the President made the brave and right call, and Americans should be proud of our service members who got the job done."