Russia launched a second day of airstrikes Wednesday against Syrian militants from an Iranian air base, rejecting US suggestions its cooperation with Tehran might violate a UN resolution as illogical and factually incorrect.
Iran confirmed on Wednesday that Russia was using its territory for the airstrikes
Russia first announced the strikes on Tuesday from near the Iranian city of Hamedan, 280 kilometers (175 miles) southwest of the Iranian capital, Tehran. On Wednesday, Russia's Defense Ministry said another wave of warplanes had departed from Iran, striking targets in eastern Syria.
According to the head of the Iranian parliament's national security and foreign policy committee, Alaeddin Boroujerdi the Russians were using Iran's Shahid Nojeh air base some 50 kilometers (30 miles) north of Hamedan, a secluded base where Russian warplanes were detected landing late last year.
Boroujerdi said the Russian Tu-22M3 bombers landed inside Iran only to refuel under the permission of the country's Supreme National Security Council, a move that allowed them to carry a larger bomb load of more than 20 metric tons.
"There is no stationing of Russian forces in the territory of the Islamic Republic of Iran," Boroujerdi added.
State Department spokesman Mark Toner on Tuesday called the Iranian deployment "unfortunate," saying the United States was looking into whether the move violated UN Security Council resolution 2231, which prohibits the supply, sale and transfer of combat aircraft to Iran.
Russia bristled at those comments on Wednesday after announcing that Russian SU-34 fighter bombers flying from Iran's Hamadan air base had, for a second day, struck Islamic State targets in Syria's Deir al-Zor province, destroying two command posts and killing more than 150 militants.
"It's not our practice to give advice to the leadership of the US State Department," Major-General Igor Konashenkov said in a statement.
"But it's hard to refrain from recommending individual State Department representatives to check their own logic and knowledge of basic documents covering international law."
Moscow first used Iran as a base from which to launch airstrikes in Syria on Tuesday, deepening its involvement in the five-year-old Syrian civil war and angering the United States.
Russia's use of the Iranian air base comes amid intense fighting for the Syrian city of Aleppo, where rebels are battling Syrian government forces backed by the Russian military, and as Moscow and Washington are working towards a deal on Syria that could see them cooperate more closely.
Russia backs Syrian President Bashar al-Assad, while the US believes the Syrian leader must step down and is supporting rebel groups that are fighting to unseat him.
On Wednesday the State Department reiterated its concern, saying Russia's use of the Iranian base "doesn't help" reach a cessation of hostilities in Syria and that US lawyers were still assessing whether it violated the UN resolution.
Russian Foreign Minister Sergei Lavrov said earlier any US dismay over Moscow's military cooperation with Iran should not distract from efforts to realize the US-Russia deal on coordinating action in Syria and securing a ceasefire.
Lavrov said there were no grounds to suggest Russia's actions had violated the UN resolution, saying Moscow was not supplying Iran with military aircraft for its own internal use, something the document prohibits.
"These aircraft are being used by Russia's air force with Iran's agreement as a part of an anti-terrorist operation at the request of Syria's leadership," Lavrov told a Moscow news conference, after holding talks with Murray McCully, New Zealand's foreign minister.