The United States dropped more than 125 bombs on Iran’s military and its allies in Iraq and Syria on Friday night as it began retaliation for attacks on American troops.

US bombers, some of which had flown across the Atlantic for the mission, hit more than 85 targets in Iraq and Syria, including sites held by the Quds Force of the Islamic Revolutionary Guard Corps (IRGC).

It is the first of a series of measures by the US to retaliate against Iranian-backed militias in Iraq and Syria, after more than 160 attacks on American forces in the last three months.

Joe Biden, the US president, vowed to retaliate for the attacks against its soldiers, saying: “If you harm an American, we will respond.”

“This past Sunday, three American soldiers were killed in Jordan by a drone launched by militant groups backed by Iran’s Islamic Revolutionary Guards Corps.

“Earlier today, I attended the dignified return of these brave Americans at Dover Airforce Base, and I spoke with each of their families.

“This afternoon, at my direction, US military forces struck targets at facilities in Iraq and Syria that the IRGC and affiliated militia use to attack US forces. Our response began today. It will continue at times and places of our choosing.

“The United States does not seek conflict in the Middle East or anywhere else in the world. But let all those who might seek to do us harm know this: If you harm an American, we will respond.”

Although the US has struck Iran’s proxy groups before, it is the first time that the US has struck Iranian military forces directly.

The strikes took place at 9pm GMT, three days after Mr Biden said he had agreed a military response to the death of three American troops at a military outpost in Jordan on Sunday.

A spokesman for the US Central Command said American forces had dropped “more than 125 precision munitions”, hitting command and control centres, rocket and missile stockpiles, drone storage sites and supply chain facilities.

The strikes came after weeks of demands by the US and its allies, including the UK, for Iran to “rein in” its proxy groups in the region after a spike in assaults on US forces that followed the outbreak of war in Gaza on October 7.

The most severe attack came on Sunday at Tower 22, a US military outpost near the Syrian border in Jordan, when three troops were killed by a suicide drone that was mistakenly identified as American.

The Pentagon later named the victims as Sgt William Rivers, 46, Specialist Kennedy Sanders, 24, and Specialist Breonna Moffett, 23. All were assigned to the 718th Engineer Company of the US Army Reserves.

The White House blamed the Islamic Resistance in Iraq, an umbrella group of Islamist forces, for their deaths and vowed to respond with force.

The fatalities are the first US combat deaths in the Middle East since 2021 when 13 personnel were killed by a suicide bomber at Kabul Airport during the withdrawal of Western forces from Afghanistan. They are also the first US deaths to be blamed on Iranian-backed groups.

Iran denied responsibility for the attack and had begun to withdraw IRGC forces from bases in Syria and Iraq in anticipation of the US strikes.

Earlier on Friday, Mr Biden witnessed the repatriation of the bodies of the US troops killed in Jordan at Dover Air Force Base, Delaware.

Speaking on Thursday at the National Prayer Breakfast in Washington DC, the president said: “They risked it all, and we’ll never forget the sacrifice and service to our country.”