It was the second straight day of Russian raids in Syria, where Moscow on Wednesday launched its first military engagement outside the former Soviet Union since the occupation of Afghanistan in 1979.

Russian President Vladimir Putin hit back at allegations that civilians had been killed, describing such claims as “information warfare”.

Moscow, a key backer of Assad, said the latest strikes hit four targets linked to the Islamic State jihadist group, which controls large parts of Syria and neighbouring Iraq.

It said the raids destroyed a “terrorist” headquarters, a weapons warehouse, a command centre and a car bomb factory.

But a Syrian security source said the strikes had targeted a powerful coalition of Islamist rebels, the Army of Conquest, which includes Al-Qaeda’s Syria affiliate Al-Nusra Front and which is fiercely opposed to IS.

The Syrian conflict, which began as an uprising against Assad’s regime in 2011, has escalated into a multi-sided civil war that has drawn thousands of jihadists from overseas.

Moscow’s escalation has worried opposition supporters, with Turkish Foreign Minister Feridun Sinirlioglu saying Thursday he felt “serious concern over the information that Russia’s air strikes targeted opposition positions instead of Daesh (IS)”.

Russian Foreign Minister Sergei Lavrov has rejected the accusations, saying Moscow saw “eye to eye” with the US on striking IS and Al-Nusra.

US Senator John McCain said Russian warplanes had targeted groups “funded and trained by our CIA”, showing that Moscow’s real priority was “to prop up Assad”.

McCain, who chairs the Senate Armed Services Committee, said he could “absolutely confirm” that the strikes hit the Free Syrian Army or other groups armed and trained by the Central Intelligence Agency.

A US-backed rebel group, Suqur al-Jabal (Falcons of the Mountain), said Russian warplanes had fired more than 10 missiles at its training camp in Idlib province.

The group has received training and equipment as part of a $500-million US programme to build an anti-IS force.

– US-Russian military talks –

A US-led coalition has carried out near-daily strikes on IS in Syria for more than a year, saying Thursday it had “not altered operations in Syria to accommodate new players on the battlefield”.

Pentagon spokesman Colonel Steve Warren told reporters that coalition planes had conducted several sorties over Syria over the past 24 hours, one of which resulted in air strikes.

Washington complained that Moscow gave just an hour’s notice of Wednesday’s Russian attacks.

The two sides were set to hold military talks Thursday on avoiding mishaps between planes from the US-led coalition and Russia, a US defence official said.

The talks, known as “deconfliction”, were due to include Elissa Slotkin, the US acting assistant secretary of defense for international security affairs.

After weeks of Russian military build-up in Syria, Russian senators on Wednesday unanimously approved armed intervention.

It remains unclear how much of the opposition fighting Assad’s army — including the Western-backed opposition — is considered by Moscow as a potential target.

Kremlin spokesman Dmitry Peskov appeared to admit that Russia was targeting not only IS, saying it operates according to a list apparently agreed with Damascus.

“These organisations are known,” he was quoted as saying by Russian news agencies. “The targets are determined in coordination with the Syrian defence ministry.”

Senior Russian foreign ministry official Ilya Rogachev told the RIA Novosti state news agency Moscow was ready to consider expanding its campaign to Iraq “if we get such a request from the Iraqi government or a Security Council resolution”.

Iraqi Prime Minister Haider al-Abadi said in a TV interview broadcast Thursday that if Russia extended the offer, “we will consider it”.

However, Lavrov later told reporters at the United Nations Moscow was “not planning to expand our air strikes to Iraq”.

– ‘Ultimatums unrealistic’ –

Russia’s defence ministry said Moscow had sent more than 50 military aircraft as well as marines, paratroopers and special forces into Syria.

“More than 50 warplanes and helicopters are part of the Russian airforce striking Islamic State targets in Syria,” defence ministry spokesman Igor Konashekov told the Interfax news agency.

Russia and the West are in deep disagreement over Syria, with Moscow backing Assad and Western powers blaming him for starting what has become a brutal war with more than 240,000 people dead and millions displaced.

Moscow has portrayed Assad as the only force stopping the spread of IS, and argues that he must be part of the conflict’s political solution.

“Life has shown that it is unrealistic to give ultimatums demanding that Assad leaves in a situation when the country is in such a crisis,” Lavrov said.