Washington, Jan 29 : US President Joe Biden has accused Iran-backed militants of being behind the attack that killed three US troops in Jordan and wounded dozens more, the media reported. Biden said that three US service members were killed and "many" wounded in a drone attack on US forces stationed in northeastern Jordan near the Syrian border, Radio Free Europe/Radio Liberty reported. "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 added in a statement. "We will carry on their commitment to fight terrorism. And have no doubt -- we will hold all those responsible to account at a time and in a manner of our choosing," Biden said on January 28. He added that the attack took place late on January 27. He did not specify the number of those injured in the incident, but a US official later said at least 34 personnel were being evaluated for traumatic brain injuries, Radio Free Europe/Radio Liberty reported. Republican Senator Tom Cotton, a vocal critic of Biden, said the "only answer to these attacks must be devastating military retaliation against Iran's terrorist forces.... Anything less will confirm Joe Biden as a coward". Jordan condemned what it called a "terrorist attack" on a military site, saying it was cooperating with the US to fortify its border defences. Earlier, a government spokesman in Amman claimed the attack was not on Jordanian soil but on a US base in Syria just across the border. The details of the attack could not immediately be verified, but reports said it occurred at Tower 22, a site hosting a contingent of US troops inside Jordan along the Syria border. Jordan is a close ally of the US in the Middle East, with the Pentagon basing some 3,000 troops there, often in support of actions in Syria. US troops have been active in Syrian in recent years battling the Islamic State (IS) extremist group and others. If confirmed to be in Jordan, the attack would be first targeting US troops in that country since the start of Israel's war in Gaza with Hamas, which has been declared a terrorist organisation by Washington and the European Union. Many observers have expressed fears of a widening conflict in the Middle East after war broke out in Gaza following Hamas's attack on Israel on October 7. At least 1,200 people were killed in those assaults, leading to retaliatory Israeli actions that have killed more than 26,000 Palestinians, according to local officials. Because of its support for Israel, US forces have been the target of Islamist groups in the Middle East, including Iranian-backed Huthi rebels based in Yemen and militia groups in Iraq who are also supported by Tehran. /IANS