Kerry in Moscow 'seeking joint bombing campaign in Syria'

US Secretary of State John Kerry, currently on his second visit to Moscow this year, is reportedly set to discuss the new military pact with President Vladimir Putin, chief backer of Syrian President Bashar Assad.

Kerry will reportedly propose to Putin that Russia and the US set up a "Joint Implementation Group" or JIG to "enable extended coordination" between their militaries on the Syrian battlefields, the leaked proposal showed.

Kerry seeks joint bombing operations, command-and-control headquarters and other synchronised efforts with Russia, the report added.

The US Secretary of State refused to discuss the proposal in detail but did not deny the report.

"I don't [want to comment on the report] right now. I'll have comments. I'm going to Moscow, meeting with President Putin tonight, and we'll have plenty of time to talk about it," Kerry said.

The Kremlin declined to comment on the newspaper report.

Russian forces in Syria are currently operating in support of Assad's regime against a variety of rebel factions while a US-led coalition focuses its fire on the IS group.

[Click to enlarge]

Any deal between the great power rivals would be controversial, since for many, including critics of President Barack Obama in Washington, it would amount to a tacit acceptance of Putin's efforts to shore up Assad's regime.

Some US officials argue that cooperation between Washington and Moscow over Syria is unfounded as both sides have opposite objectives in the country.

"It isn't clear why the secretary of state thinks he can enlist the Russians to support the administration's goals in Syria," a US intelligence official told Reuters.

"He's ignoring the fact that the Russians and their Syrian allies have made no distinction between bombing ISIS and killing members of the moderate opposition, including some people that we've trained," the official said, using an acronym for the militant group.

"Why would we share intelligence and targeting information with people who've been doing that?" he added.

Kerry is due in Moscow later Thursday and is set to hold talks with Putin at the Kremlin followed by a meeting with Foreign Minister Sergei Lavrov on Friday

Kerry is due in Moscow later Thursday and is set to hold talks with Putin at the Kremlin followed by a meeting with Foreign Minister Sergei Lavrov on Friday.

Both IS and al-Qaeda affiliate al-Nusra Front are defined as terrorist groups by the UN Security Council, and they are not party to the much-breached ceasefire in place between Assad's forces and more moderate rebel groups.

But, while the IS's so-called "caliphate" has global ambitions, al-Nusra Front has concentrated on battling Assad, fighting alongside other rebel groups backed by US allies.

Any deal between Russia and the US to fight both groups would in effect strengthen Assad's position, and could undermine US efforts to press him to agree a negotiated political settlement to the civil war.

Agencies contributed to this report.