A US airstrike on a Baghdad airport on Friday killed the top general directing Iran’s proxy wars in neighbouring countries, making good on a promise by US President Donald Trump to strike back at Tehran for its alleged role in the storming of the US embassy in Iraq earlier this week.

Oil prices jumped following the killing as rising tensions stoked fears of supply disruptions from the Persian Gulf region, which supplies about 25% of the global crude consumption.

Crude initially soared by as much as 4%, the highest level since 17 September following missile and drone attacks against Saudi oil installations.

Prices retreated later but remained well above their recent levels amid fears of regional escalation and threat to Iraqi exports.

Major-General Qassem Soleimani, head of the elite Quds Force and architect of Iran’s spreading military influence in the Middle East, died along with his adviser Iraqi militia commander Abu Mahdi al-Muhandis.

The incident is likely to further worsen relations between Tehran and the US, which has imposed severe sanctions on Iran to prevent it from exporting oil.

Iran’s Supreme Leader Ayatollah Ali Khamenei vowed tough revenge for the killing of his top military emissary abroad.

The storming of the embassy followed a US air raid last week on the pro-Iranian Kataib Hezbollah militia, founded by Muhandis.

“At the direction of the president, the US military has taken decisive defensive action to protect US personnel abroad by killing Qassem Soleimani,” the Pentagon said in a statement.

“This strike was aimed at deterring future Iranian attack plans.’’

US officials said Soleimani was killed in a drone strike. Iran’s Revolutionary Guards said the general was killed by US helicopters.

Khamenei said harsh revenge awaited the “criminals” who killed Soleimani.

“All enemies should know that the jihad of resistance will continue with a doubled motivation, and a definite victory awaits the fighters in the holy war,” Khamenei said in a statement carried by state television, in which he called for three days of national mourning.

Tensions have been rising for months between Washington and Tehran, which has been fighting US influence in the Middle East.

US officials blamed Iran for the devastating missiles and drones attack on oil installations of Saudi Aramco, the world’s largest oil exporter. The Trump administration did not respond then, beyond heated rhetoric and threats.

Soleimani, who has led the foreign arm of the Revolutionary Guards and has had a key role in fighting in Syria and Iraq, acquired celebrity status at home and abroad.

He survived several assassination attempts against him by Western, Israeli and Arab agencies over the past two decades.

His Quds Force, tasked with carrying out operations beyond Iran’s borders, offered vital support to Syrian President Bashar al-Assad when he looked close to defeat in the civil war raging since 2011.

He also played a significant role in the defeat of the so-called Islamic State in Iraq.

Soleimani became head of the Quds Force in 1998, a position in which he kept a low profile for years while he strengthened Iran’s ties with Hezbollah in Lebanon, Syria’s government and Shia militia groups in Iraq.