An Iran-backed militia in Syria fired several rockets toward northern Israel in the predawn hours of Monday morning, but they fell short of the border, the army said.

According to the Israel Defense Forces, the attack was carried out by operatives of a Shiite militia operating under the command of Iran’s Islamic Revolutionary Guard Corps’ Quds Force.

The IDF said the rockets were fired from the suburbs outside Damascus.

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The alleged attack came amid reports of a series of airstrikes against a pro-Iranian militia in eastern Syria, which killed 18 fighters, according to a Britain-based war monitor.

In a statement, the IDF said it “holds the Syrian regime responsible for every action that takes place in Syria.”

In a tweet, the Israeli army’s Arabic-language spokesperson warned Syria’s Assad regime that it would “pay the price” for allowing Iran and its proxies to use Syria as a base of operations against the Jewish state, either by turning a blind eye to their actions or by actively cooperating with them.

“This is not hidden from us,” the spokesman wrote.

According to the Syrian Observatory for Human Rights, the airstrikes on pro-Iranian militias took place in the Albu Kamal region near the border with Iraq.

There have been no official claims as to who was behind the attack.

“Warplanes whose identity is not known so far targeted vehicles and positions of the Iranian forces and militias loyal to them,” the Observatory said. “Eighteen fighters were killed, but their nationalities have not yet been determined.”

The blasts targeted a base belonging to the Popular Mobilization Force, according to the Saudi-owned Al Arabiya network, citing sources in the area.

Al Arabiya said the base, in the al-Boukamal area, also housed forces from the Lebanese Hezbollah terror group.

Since mid-July, five arms depots and training camps belonging to the Popular Mobilization Forces have been targeted in apparent attacks.

The PMF has blamed both Israel and the US for a recent string of blasts and drone sightings at its bases. There was no immediate comment from Israel.

Sunday night’s blasts occurred on the Syrian side of the border in the same regions where Fox News reported last week Iran was constructing a new military facility that can house thousands of soldiers and storage facilities for advanced weapons.

It was not immediately clear if this was the same base.

Quoting Western intelligence sources, the US cable network said the base is located near the Syria-Iraq border, and its construction is being overseen by the Quds Force, the overseas branch of Iran’s elite Islamic Revolutionary Guard Corps.

Satellite photos of the base, known as the Imam Ali compound, showed what appeared to be five recently constructed buildings that can store precision-guided missiles, according to ImageSat International.

ImageSat, an Israeli satellite imagery analysis firm, said the photos also show other structures at the facility that could be used for storing missiles.

The images also show what appears to be Iranian construction on a new border crossing that near the existing al-Qaim border crossing with Iraq.

Israel views Iran as its greatest threat, and has acknowledged carrying out scores of airstrikes in Syria in recent years aimed primarily at preventing the transfers of sophisticated weapons, including guided missiles, to the Iran-backed Hezbollah.

This quiet war has reportedly expanded to Iraq in recent weeks, with US officials saying the Israel Defense Forces was behind at least some strikes on Iran-linked sites outside of Baghdad.

The Pentagon, which is mindful of not alienating Iraq’s leadership and jeopardizing its military presence in the country, has pointedly distanced itself from the mysterious explosions.

The PMF was established in 2014 from mostly Shiite paramilitary groups and volunteers to fight the Islamic State jihadist organization and is now formally part of Iraq’s armed forces.

But the US and Israel fear some units are an extension of Iran and have been equipped with precision-guided missiles that could reach Israel.

Last month, an Israeli airstrike in Syria thwarted what Israel said was a plot by Iran to launch a series of explosives-laden attack drones meant to crash into Israeli targets. Iran denied the claims.

Hours later, Israel allegedly struck Iran-linked targets as far away as Iraq and crash-landed two drones in Hezbollah-dominated southern Beirut.

Iran, its allied militias and Russia have backed Syrian President Bashar Assad in the country’s devastating eight-year civil war.

The Syrian conflict, which broke out in 2011 with the bloody repression of anti-regime demonstrations, has become a complex war, dragging in regional and international powers and leaving more than 370,000 people dead.

AFP contributed to this report.