Airstrikes believed to be from Israel again targeted an Iranian base in Syria that reportedly houses Russian troops, this time killing four members of Iran’s Revolutionary Guard Corps (IRGC), currently fighting on behalf of Syrian dictator Bashar al-Assad, Tehran confirmed on Monday.

Russia, Iran, and the United States have reportedly attributed the strike to Israel.

Acknowledging that Israel has “attacked the T-4 base near Homs twice in the past, destroying an Iranian drone control center and communications systems, where defense analysts say there are large deployments of Russian forces, and where jets fly regular sorties to strike rebel-held areas,” Haaretz reports:

The Russian military said on Monday that two Israeli F-15 war planes carried out airstrikes on a Syrian air base near Homs on Sunday, the Interfax news agency reported. [Fourteen] people were reportedly killed in the strike, at least four of them Iranians. Interfax cited the Russian Defense Ministry as saying the Israeli war planes had carried out the strikes from Lebanese air space. The Russian ministry said that Syrian air defense systems had shot down five of eight missiles fired, while the other three landed in the western part of the base.

While Dmitry Peskov, spokesman for Russian President Vladimir Putin, told reporters on Monday that Israel failed to warn Moscow of the air strike, American officials told NBC News that Israel “fired the missiles after informing Washington.”

Haaretz notes that Israel has not acknowledged the attack “as part of its policy of not directly taking responsibility for actions in the Syrian arena.”

According to the Syrian Observatory for Human Rights, a U.K.-based organization that monitors the civil war using a network of ground sources, the strike killed at least 14 people, including some fighters from various nationalities and others linked to both the Iranian military and Tehran’s narco-terrorist proxy Hezbollah.

Reuters reports:

Four Iranian military personnel were killed in an air strike on a Syrian air base on Sunday, Iran’s Fars news agency said, as Syria and its main allies Iran and Russia blamed Israel for carrying out the attack. Israel has not confirmed or denied mounting the raid, but Israeli officials said the Tiyas, or T-4, air base near Homs was being used by troops from Iran, and that Israel would not accept such a presence in Syria by its arch foe.

Pro-Iranian media outlets reportedly identified the four military advisers as IRGC members.

Most of the fatalities “were either Iranians or members of Iran-backed groups” fighting on Assad’s side, like the terrorist group Hezbollah, indicated Rami Abdurrahman, the chief of the Britain-based Observatory, according to Haaretz.

Echoing Russia in a telegram message to the United Nations, Syria’s Foreign Ministry deemed the strike as a U.S.-assisted act of “terror,” Ynet news reports.

Syria’s Foreign Ministry told the U.N.:

The Israeli attack constitutes an indirect response to the success of the Syrian Arab Army in eliminating armed terrorist groups from the Damascus suburbs and other Syrian areas. Israel’s continued aggression wouldn’t be possible without the US administration’s absolute support, and the immunity it gives it to continue its acts of terror and to threaten peace and security in the Middle East and in the entire world.

Syrian dictator Bashar al-Assad now controls more territory than any of the other warring parties in the country, courtesy of the military assistance provided to the regime by Russia and Iran.

Israel, which shares a border with Syria, has neither confirmed nor denied the attack, but it has warned that it would not accept Iranian’s military presence at the targeted air base near Homs, reports Reuters.

On Monday, Prime Minister Benjamin Netanyahu declared, “We have one clear and simple rule and we seek to express it constantly: if someone tries to attack you – rise up and attack him.”

The IRGC has been helping Assad throughout most of the Syrian civil war, which has been raging since March 2011.

“More than 1,000 Iranians have been killed in Syria, including senior members of the Guards,” Reuters points out. “The semi-official Fars news said on Monday that four ‘defenders of the shrine’ were killed in the air strike.”

In an April 4 statement issued after a phone call between Netanyahu and U.S. President Donald Trump, the White House noted that the two leaders spoke about “recent developments in the Middle East.”

Trump “reiterated the commitment of the United States to Israel’s security and the two leaders agreed to continue their close coordination on countering Iran’s malign influence and destabilizing activities,” the White House notes.