General Qasem Soleimani, the head of the Iranian Revolutionary Guards' elite Quds Force, has been killed by US forces in Iraq.
The Pentagon confirmed he was killed "at the direction of the president".
It comes after reports of a strike at Baghdad's international airport, which is said to have killed a number of people.
Iran's Revolutionary Guards also confirmed Gen Soleimani was dead, blaming an attack by US helicopters.
They also said Iraqi militia leader Abu Mahdi al-Muhandis had been killed.
"At the direction of the President, the US military has taken decisive defensive action to protect US personnel abroad by killing Qasem Soleimani," a Pentagon statement said.
"This strike was aimed at deterring future Iranian attack plans. The United States will continue to take all necessary action to protect our people and our interests wherever they are around the world."
Reports also suggest that a number of Iraq militia heads have been detained by US forces in Baghdad, although this is unconfirmed.
WASHINGTON (AP) — The New Year’s Eve attack on the U.S. Embassy compound in Baghdad has exposed a deepening divide between the United States and Iraq over Iran’s role there, even as the Pentagon embarks on a more aggressive mission to counter Iranian influence across the Mideast.
“The game has changed,” Defense Secretary Mark Esper said Thursday, telling reporters that violent acts by Iran-backed Shiite militias in Iraq — including a rocket attack on Dec. 27 that killed one American — will be met with U.S. military force. The U.S. had retaliated by launching air strikes that killed 25 fighters of an Iran-back militia.
In a reflection of that tougher stance, upwards of 700 U.S. Army paratroopers arrived in Kuwait on Wednesday from their base at Fort Bragg, North Carolina. Esper said they are “defensive support” that can be used if there is more trouble in Baghdad or elsewhere in the region. Gen. Mark Milley, chairman of the Joint Chiefs of Staff, said additional forces are on alert to deploy, although he said no decision has been made yet to augment the battalion of paratroopers.
Milley, who has combat experience in Iraq, said Iraqi security forces are capable of preventing Iran-backed groups from threatening U.S. interests in Iraq.
“It’s a question of political will,” he said, alluding to the central issue of whether Iraq will choose to sustain its U.S. partnership, which many Iraqis see as an infringement on their sovereignty.
Parts of Iraqi society, on the other hand, detest Iran’s influence, including the role of Iran-backed militias in the Popular Mobilization Forces, which are an auxiliary of the Iraqi security forces and nominally under Iraqi government control. The political influence of the Popular Mobilization Forces has risen in recent years, and their allies dominate the parliament and government. That has made them the target of anti-government protesters, who have attacked Iranian diplomatic missions and the local headquarters of parties affiliated with the militias across southern Iraq.
The U.S.-Iraq relationship, shaped in large part by the 2003 U.S. invasion to topple President Saddam Hussein, has been shaky for years. The invasion unleashed Sunni insurgent violence that had abated by 2011 but was followed in 2014 by the rise of the Islamic State extremist group, which swept across the Syrian border to capture wide swaths of Iraqi territory. U.S. forces returned to help Iraq regain control, but Iranian influence since has grown more overt.
The tensions in Iraq are amplified by the Trump administration’s campaign to squeeze Iran. In 2018 it withdrew from the Iran nuclear deal and imposed economic sanctions, hoping to compel Tehran to negotiate a new and broader nuclear agreement. Iran in response has targeted military, diplomatic and economic interests of the United States and its Gulf allies through proxy forces like the group that attacked the U.S. Embassy compound in Baghdad.
The U.S. has about 5,200 troops in Iraq, mainly to train and advise Iraqi security forces fighting Islamic State remnants. Esper said the Pentagon has been studying a possible scaling down of that force, but he stressed that this is distinct from determining the type and number of combat forces that are needed to deal with Iran-related attacks like Tuesday’s. The U.S. has thousands of forces elsewhere in the Gulf, including in Kuwait, Qatar, Saudi Arabia and Bahrain.
In his remarks at the Pentagon, Esper said the Iraqi government has fallen short of its obligation to defend its American partner. While saying the government’s effort has “greatly improved” since Tuesday’s storming of the U.S. Embassy compound by members of Kataeb Hezbollah, or KH, an Iran-supported militia proxy, Esper made clear his disappointment.