Washington DC - American and allied forces in Syria were targeted with rockets on Monday, a US defense official said, after three of Washington's troops were killed in a drone attack in Jordan the previous day.

US forces in Iraq and Syria have faced a surge in attacks since mid-October, many of them claimed by a loose alliance of Iran-backed militant groups that oppose American support for Israel in the Gaza conflict.

"Multiple rockets were launched against US and coalition forces at Patrol Base Shaddadi, Syria. No injuries reported and no damage to infrastructure," the US defense official said on condition of anonymity, referring to an installation in northeastern Syria.

The United States has some 900 troops in Syria and 2,500 in neighboring Iraq as part of the international coalition against the Islamic State group, a jihadist organization that once controlled swathes of both countries.

US and coalition forces have been attacked at least 165 times since mid-October – 66 in Iraq, 98 in Syria, and one in Jordan – with "a mix of one-way attack drones, rockets, mortars, and close-range ballistic missiles," the US official said.

Dozens of American personnel have been wounded in previous attacks, but none had been killed by hostile fire in the Middle East since the start of the Israel-Hamas war until Sunday when a drone attack left three dead and more than 30 wounded.

On Monday the White House vowed a "very consequential response" to the deadly attack in Jordan, which has raised fears of an escalating conflict in the Middle East.

Anger over Israel's campaign in Gaza – which it launched after an unprecedented attack by Hamas in October – has grown across the region, with violence involving Iran-backed groups in Lebanon, Iraq, Syria, and Yemen.