Three American troops have been killed and 34 injured in a drone attack in Jordan.

Those killed in the attack were sleeping in a tent at a place called Tower 22 in northeast Jordan, near the Syria border, and some of those injured are being evacuated from the country.

US President Joe Biden said the attack was carried out by “radical Iran-backed militant groups” in Syria and Iraq on Saturday night.

Follow live: Biden blames ‘radical Iran-backed militant groups’

“While we are still gathering the facts of this attack, we know it was carried out by radical Iran-backed militant groups operating in Syria and Iraq,” he said in a statement.

The Pentagon has still not released details on the types of injuries sustained, but a US official said 34 personnel are being monitored for possible traumatic brain injuries – which is a common occurrence after a large blast.

An earlier statement from the US military had said 25 were injured in the attack.

It’s the first time US troops have been killed in the region since war began in Gaza.

“We will carry on their commitment to fight terrorism,” Mr Biden continued, referring to the “patriots” who died in the attack.

“And have no doubt – we will hold all those responsible to account at a time and in a manner of our choosing.”

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A spokesman for Jordan’s government, however, said the attack did not happen on their soil and insisted it was in Syria. They said the attack did not result in the injury of any Jordanian border guards.

The US has long used Jordan – which neighbours Iraq, Israel, the Palestinian territory of the West Bank, Saudi Arabia and Syria – as a basing point, with about 3,000 troops typically stationed there.

Since the war in Gaza began, US troops in Iraq and Syria have faced drone and missile attacks on their bases, but this was the first time they’ve been attacked in Jordan.

Attack shows how war in Gaza is spreading through Middle East

The deaths of three US soldiers are the first since 7 October and because of the location, the Jordanian border, and the anticipated American response, this is certainly an escalation in the wider Middle East conflict.

The target, Tower 22, is not a conventional US military outpost in the region.

It’s a crossing point between Jordan and Syria, established since at least 2015 and used as an infiltration point for US special forces to enter and exit Syria.

While the base is on the Jordanian side of the border, the attacks were likely launched from within Syria.

Jordan has publicly distanced itself from these attacks, which might have something to do with Jordan’s preference that US military presence on their soil is kept below the radar, but it equally might point to a special operations position that wasn’t as well guarded as more established bases.

It also suggests an intelligence failure to prevent the attack.

Ever since 7 October, Jordan, with its large Palestinian population, has been deeply concerned the conflict would spread there.

The White House blames Iranian-backed militia, which is an obvious call, but could cover any number of groups.

The most likely is Kata’ib Hezbollah, a radical Shia group. They mustn’t be confused with the better-known and larger Hezbollah in Lebanon, although both have strong links to Iran and probably each other.

US forces have been targeted on many occasions in Iraq and Syria since 7 October, although many of these attacks have gone somewhat under the radar.

However, in recent weeks, America has been hitting Kata’ib Hezbollah hard. This attack could be a retaliation for that.

If nothing else, this again shows how the war in Gaza is spreading through the Middle East.

America, as Israel’s staunch ally, is finding itself increasingly dragged into multiple smaller-scale skirmishes around the region, whether it be in the Red Sea, Iraq, or, as was demonstrated over the past 24 hours, on the Jordan-Syria border.

The hope is that a ceasefire in Gaza, possibly close, will see things calm down elsewhere, but every passing week sees the fallout of Israel’s war affect other parts of the Middle East.

While US officials are still working to identify the precise group responsible for the attack, they believe one of several Iranian-backed groups are responsible.

The identities of the military service members killed will be withheld for 24 hours until their next of kin have been informed, say US officials.

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The attack is a major escalation in the Middle East, where war broke out after Palestinian Islamist group Hamas attacked Israel on 7 October, killing 1,200 and taking dozens to Gaza as hostages.

Israel’s subsequent assault on Gaza has killed more than 26,000 Palestinians, according to the local health ministry.

While the US has maintained it is not at war in the region, it has – along with the UK – made strikes against targets of Yemen’s Houthi groups, which have been attacking commercial vessels in the Red Sea.