Three United States service members were killed and "many" wounded Saturday in a drone attack on US forces stationed in northeastern Jordan near the Syrian border, US Central Command said.
President Joe Biden on Sunday blamed Iran-backed groups for the attack and has vowed reprisals.
"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," Biden said in a statement released by the White House.
Wounded soldiers evacuated for further treatment
US Central Command said at least 25 service members were wounded, but the number might rise. Two different officials told the Reuters news agency some wounded soldiers were medically evacuated from the base for further treatment.
Another said the drone struck near the barracks, which, if confirmed, could explain the high number of casualties.
Latest in a series of attacks on US and allied forces
The tensions in the region have been rising since the beginning of the Israel-Hamas war, and the attack may exacerbate the situation.
A Senior official with the Palestinian militant group Hamas, Sami Abu Zuhri, directly tied the incident to the war in Gaza.
"The killing of three American soldiers is a message to the U.S. administration that unless the killing of innocents in Gaza stops, it must confront the entire nation," he told Reuters.
The deaths were the first fatalities of US troops in the region since the conflict began.
There had been over 150 attacks on US and coalition forces in Iraq and Syria since the war began, the Pentagon said. In response, Washington has carried out retaliatory strikes in both countries.
Many of the attacks on US personnel have been claimed by the Islamic Resistance in Iraq, a loose alliance of Iran-linked armed groups that oppose US support for Israel in the Gaza conflict.
"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.
Dispute about exact location of the attack
Speaking to Jordanian public broadcaster al-Mamlaka, Muhannad Mubaidin, a government spokesman, insisted the attack happened outside of the kingdom across the border in Syria.
US officials insisted the attack happened at a base in Jordan, known as Tower 22, near the Syria border.
US troops have long been based in Jordan, up to 3,000 American soldiers are typically are stationed there.