IRAN launched a barrage of missiles at United States forces in the Middle East early this morning as the US partnered with Saudi Arabia to strike militias in neighbouring Iraq, killing at least 20 fighters.

The flare-up after several days of relative calm raised the risk of a return to all-out war. 

It also underscored the difficulty of ending the illegal and unprovoked war unleashed by the US and Israel on Iran on February 28.

It was also likely to add to concerns that the US is further drawing down already diminished stockpiles of sophisticated munitions.

Saudi Arabia had accused the Iraqi militias of firing drones against its oil facilities over the past two days. 

An umbrella group of Iraqi militias initially denied the allegations, while the Houthi-led government in Yemen said they had attacked Saudi energy facilities as part of a separate but related conflict.

Mediators had expressed optimism about bringing the US and Iran back to the negotiating table. 

An interim agreement collapsed in recent weeks over renewed fighting in the Strait of Hormuz, a crucial waterway for global energy supplies that Iranian attacks have again effectively closed.

The renewed hostilities sent oil prices spiking. Brent crude, the international standard, jumped 3.1 per cent to $84.58 (£64) a barrel.

Iran’s paramilitary Revolutionary Guard said that it fired ballistic missiles at the Muwaffaq Salti Air Base and the headquarters of the US military’s Central Command in Jordan, in a statement carried by the IRNA news agency.

Jordan’s military said five Iranian missiles had been intercepted and destroyed. There were no immediate reports of casualties or damage.

The US military later announced that US and Saudi fighter aircraft had struck multiple logistics and weapons sites in eastern Iraq in response to the alleged drone attacks on Saudi Arabia. 

The Saudi Defence Ministry warned that it “does not seek escalation but will respond to any aggression.”

The Popular Mobilisation Forces, a coalition of primarily Shi’ite, armed groups that is officially under the command of the Iraqi military, said at least 20 fighters were killed and 32 others wounded in the overnight strikes.

The office of Iraqi President Nizar Amidi condemned Wednesday’s US-Saudi air strikes, calling them “an unacceptable attack and a blatant violation of Iraq’s sovereignty, targeting its official security institutions.”

It called for dialogue and de-escalation.

Iraqi Prime Minister Ali al-Zaidi called an emergency meeting of the country’s National Security Council on Wednesday to discuss the strikes.