A US drone strike in Iraq has killed Iran's most senior military leader General Qasem Soleimani, commander of the Iranian Revolutionary Guard's elite Quds Force.
Soleimani has led Iran's military operations across the Middle East for many years and his targeted killing is a major escalation in the conflict between Washington and Tehran.
Soleimani was killed shortly after landing at Baghdad airport on 3 January.
Senior figures from local Iran-backed militias are also reported to have been killed in the attack.
A statement from the Pentagon said that the strike was ordered by US President Donald Trump.
It described the strike as 'decisive defensive action' taken to prevent attacks against US personnel and interests in the region.
The Pentagon said that Soleimani "was actively developing plans to attack American diplomats and service members in Iraq and throughout the region".
Tehran has reacted furiously and has promised to retaliate.
Iran's Supreme Leader Ayatollah Ali Khamenei said "severe revenge awaits the criminals" behind the attack before attending an emergency meeting of Iran's national security council.
Khamenei also announced three days of national mourning.
In a decree issued on 3 January, Khamenei named Brigadier General Esmail Qaani as new commander of the Quds Force. Khamenei described Qaani as “one of the most distinguished Revolutionary Guard commanders”.
Qaani fought in the Iran-Iraq war of the 1980s and was a close aide to Soleimani. He also served as an intelligence official in the Islamic Revolution Guard Corps (IRGC).
Qaani is described as being known for his hardline opposition to Israel, similar to Soleimani, and one of the key figures in Iran’s involvement in the Syrian civil war.
Hailed as a national hero, Suleimani was seen as one of the most powerful figures in Iran. His Quds Force reported directly to the Ayatollah.
Under his leadership, Iran supported Hezbollah in Lebanon and other pro-Iranian militant groups.
Soleimani expanded Iran's military presence in Iraq and Syria and masterminded Syria's offensive against rebel groups in the country's long civil war.
The US describes Soleimani and the Quds Force as terrorists and holds them responsible for the deaths of hundreds of US personnel.
President Trump tweeted an image of the US flag shortly after the news broke.
Trump later tweeted that Soleimani was “directly and indirectly responsible for the death of millions of people,” and that the military leader “should have been taken out many years ago!”
In another tweet on 3 January, the US president said: “Iran never won a war, but never lost a negotiation!”
It is not clear what Trump meant by the tweet, but it has led to speculation that he is attempting to force Tehran into negotiations with Washington and its allies.
The assassination of Soleimani has raised concerns about a new war in the region. Fears of significant, long-term disruption to Middle East oil supplies saw oil prices jump by more than 4 per cent following news of the attack.
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