MOSCOW, August 17. /TASS/. Russia’s Sukhoi-34 planes took off from an airdrome in Iran on Wednesday to hit Islamic State facilities in Syria’s Deir ez-Zor province and eliminate more than 150 militants, the Russian Defense Ministry has told the media.

"Russia’s Sukhoi-34 bombers from the Hamadan airdrome in Iran dealt a massive air strike against facilities of the terrorist organization Islamic State in Deir ez-Zor province. The planes carried the maximum payload of high explosive fragmentation bombs OFAB-500," the Defense Ministry said.

"As a result of the strike two command centers and large field training camps of the Islamic State near Deir ez-Zor were destroyed. More than 150 militants, including foreign mercenaries were killed," the Defense Ministry said.

Sukhoi-35 fighter jets operating from the Hmeymim airdrome, in Syria, provided protection.

"After accomplishing their mission all Russian planes returned to base," the Defense Ministry said.

Use of Iranian airfield doesn't mean Russian arms supplies to Tehran

Russia’s Aerospace Force for the first time used Iran’s Hamadan airdrome to attack terrorists in Syria on August 16. Sukhoi-34 and long-range Tupolev-22M3 bombers participated in the raid. They hit facilities of terrorist groups Islamic State and Jabhat al-Nusra (both outlawed in Russia) in Syria’s provinces Aleppo, Deir ez-Zor and Idlib.

Mark Toner, a spokesman for the US Department of State, told reporters that Washington is exploring whether Russia’s use of an Iranian air base to hit extremists in Syria is a violation of a UN Security Council resolution. He noted that "it could very well be a violation of UN Security Council resolution 2231, which ... prohibits the supply, sale or transfer of combat aircraft to Iran unless approved in advance by the UN Security Council."

A source in the Russian Foreign Ministry has stressed that the use of an Iranian airfiled by the Russian Aerospace Force doesn't contradict the UNSC resolution prohibiting arms supplies to Tehran

"The Americans need to read UN Security Council Resolution 2231 more attentively," the source said. "The wording of the relevant paragraph concerning supplying weapons to Tehran has nothing to do with the situation with Russian aircraft in Iran."

UN Security Council 2231 was passed unanimously on July 20, 2015. The document approved the deal reached by a group of six world powers (five permanent members of the UN Security Council plus Germany) and Iran (the so-called Joint Comprehensive Plan of Action on Iran’s nuclear program). The resolution envisages all necessary mechanisms to implement this plan.