The US government has released the names of three troops killed by an enemy drone attack in Jordan on Sunday.
Sgt William Jerome Rivers, 46, Specialist Kennedy Ladon Sanders, 24 and Specialist Breonna Alexsondria Moffett, 23 were killed when a drone hit their housing unit.
The US has blamed Iranian-backed groups and the Pentagon said it carried the "footprints" of Kataib Hezbollah.
The Pentagon also reiterated the US does not want a war with Iran.
"We don't seek war, but we will take action, and respond to attacks on our forces," said Pentagon spokesperson Sabrina Singh.
CBS News, the BBC's US partner, said it was told by a US official that the drone used in the attack appeared to be Iranian-made.
The official indicated it was a "type of Shahed drone," which is a one-way attack drone Iran has been providing to Russia.
Iran has denied US and British accusations that it supported militant groups blamed for the strike.
The Pentagon said the three soldiers killed on Sunday morning came from an army reserve unit based in Fort Moore, in the state of Georgia.
Lt Gen Jody Daniels, Chief of Army Reserve and Commanding General US Army Reserve Command, paid tribute to the fallen soldiers.
"On behalf of the Army Reserve, I share in the sorrow felt by their friends, family, and loved ones. Their service and sacrifice will not be forgotten, and we are committed to supporting those left behind in the wake of this tragedy", said Gen Daniels.
The drone attack took place in Rukban, north-eastern Jordan, near the Syrian border. The base was later named by US officials as Tower 22.
More than 40 military personnel were injured when the unmanned aerial system hit the container housing unit they were in on Sunday morning.
Features of an air defence system were turned off at Tower 22 at the time of the attack, US officials told CBS News, because the enemy drone arrived at the same time as a returning US drone.
They added that troops at the air base were still in their sleeping quarters when the drone struck - with little to no warning.
Iran has denied playing a part in supporting groups suspected of being responsible for the strike.
Nasser Kanaani, Iran's foreign ministry spokesman, said it was "not involved in the decision making of resistance groups" in how they chose to "defend Palestinians or their own countries".
Iran's Intelligence Minister Esmail Khatib said that regional armed groups aligned with Iran respond to "American aggressors" at their own discretion.
US President Joe Biden said the US "will hold all those responsible to account at a time and in a manner of our choosing".
The US Defence Secretary Lloyd Austin said he and Mr Biden would take "all necessary actions" following the attack on American forces.
Pentagon spokeswoman Sabrina Singh said the attack was carried out by an Islamic Revolutionary Guard Corps-backed militia and had the "footprints" of Iraq-based militant group Kataib Hezbollah.
The Islamic Resistance in Iraq has claimed it was behind the attack.
The umbrella group emerged in late 2023 and is comprised of several Iran-affiliated militias operating in Iraq. It has claimed other attacks against US forces in recent weeks.
In a statement, the group said it had targeted three US bases in Syria - identifying them as Shaddadi, Tanf and Rukban. However, Rukban is on the Jordanian side of the border with Syria. The group also said it targeted an Israeli oil facility in the Mediterranean.
It is the first time that a strike has killed US troops in the region since the start of the war in Gaza, triggered by Hamas's 7 October attack on Israel.
There have been other attacks on US bases in the region, but before Sunday there were no fatalities, according to the US military.
Officials said that US sites in Iraq and Syria had been attacked at least 165 times since 17 October.
Last month, the US carried out airstrikes against Iran-affiliated groups after three US servicemembers were injured, one critically, in a drone attack on a base in northern Iraq.
Earlier in January, one retaliatory US strike in Baghdad killed a militia leader accused of being behind attacks on US personnel.
Source: BBC