US F-15 fighter jets carry out airstrike against weapons facility used by Iran in Syria

The United States has carried out an airstrike on a weapons storage facility in eastern Syria using two F-15 fighter jets, the Pentagon has announced.

For the second time in recent weeks, the US has carried out strikes against a weapon storage facility in eastern Syria that the Pentagon said was used by Iran's Islamic Revolutionary Guard Corps (IRGC) and affiliated groups.

An Islamic Revolutionary Guard Corps (IRGC) military personnel holds a Palestinian flag (Getty)

Tensions continue to soar over the Israel-Hamas conflict, U.S. and coalition troops have been attacked at least 40 times in Iraq and Syria by Iran-backed forces since the start of October.

Forty-five U.S. troops have suffered traumatic brain injuries or minor wounds amid growing concern that the conflict could spread through the Middle East and turn U.S. troops at isolated bases into targets.

In a statement, U.S. Defence Secretary Lloyd Austin said the strikes were conducted by two U.S. F-15 fighters and were in response to the recent attacks against U.S. forces.

"If attacks by Iran's proxies against U.S. forces continue, we will not hesitate to take further necessary measures to protect our people," Austin said.

A senior U.S. military official, speaking on the condition of anonymity, said the military had watched the location in Deir al Zor province for some time and was confident there were no civilian casualties.

The official said the military had tracked a "couple" of people near the facility overnight, though they were not believed to be civilians and an analysis was ongoing to see if anyone was killed.

The United States has occasionally carried out retaliatory strikes against Iranian-backed forces in the region after they attack American forces.

On Oct. 26, U.S. forces attacked two facilities used by the IRGC and groups its backs.

The United States has 900 troops in Syria, and 2,500 more in neighbouring Iraq, on a mission to advise and assist local forces trying to prevent a resurgence of Islamic State, which in 2014 seized large regions of both countries but was later defeated.

The USS Gerald R Ford during a fuelling-at-sea on October, 11 (Reuters)

Earlier on Wednesday, a U.S. MQ-9 drone was shot down near Yemen by the Iran-aligned Houthi movement over the Red Sea.

Officials said the drone was believed to be in international waters when it was shot down.

The United States has sent warships and fighter aircraft to the region since the Israel-Hamas conflict erupted on Oct. 7, including two aircraft carriers, to try to deter Iran and Iran-backed groups.

The number of troops added to the region is in the thousands.

It's understood the U.S. military was taking new measures to protect its Middle East forces during the ramp-up in attacks by suspected Iran-backed groups, and was leaving open the possibility of evacuating military families if needed.

The measures include increasing U.S. military patrols, restricting access to base facilities and boosting intelligence collection, including through drone and other surveillance operations, officials say.