In a telephone conversation at Russia’s behest, the two men ‘exchanged views on regional security matters, first and foremost’.

Russian President Vladimir Putin spoke to Saudi Arabia’s King Salman about finding a solution to the Syria crisis on Saturday, just two days before he is due to address the UN on the issue, the Kremlin said.

In a telephone conversation at Russia’s behest, the two men “exchanged views on regional security matters, first and foremost, in the context of finding ways to settle the conflict in Syria”, a statement posted to the Kremlin’s website said.

They also discussed “building more effective international cooperation in the fight against the so-called ISIS and other terrorist groups”, it said.

The Saudi Press Agency reported that “Putin congratulated the king on [the Muslim holiday] Eid Al Adha” and “expressed condolence on the [Hajj] stampede accident,” that killed at least 769 people last Thursday.

A decades-long backer of the Damascus regime, Moscow has steadfastly supported President Bashar al-Assad throughout four-and-a-half years of war which have killed more than 240,000 people.

Saudi Arabia is part of a U.S.-led coalition that began an air campaign against ISIS in Syria last September, and insists it will never cooperate with the Assad regime.

On Monday, Putin will address the General Assembly in New York to outline his plan for Syria, notably the idea of expanding a coalition, which would include Assad’s army, to fight Islamic State.

He will also meet US President Barack Obama on the sidelines of the gathering, their first formal talk in two years.

Russia has lately boosted its military presence in Syria, deploying more troops and warplanes to an air base along with new arms deliveries to Assad’s forces. Last week, the Syrian army used Russian drones against the jihadists for the first time.

On Saturday, a Syrian military source told AFP that at least 15 Russian cargo planes transporting “equipment and personnel” had landed at the Hmeimim military base in western Syria in the past two weeks.

Moscow’s military build-up comes with Washington’s own policy for fighting ISIS in Syria in increasing disarray.

The U.S. has a $500-million program to train and equip vetted moderates recruited from among the rebels fighting Assad, but it has faced repeated setbacks.

Washington and its allies have up until now insisted that Assad has no future in Syria, but there have been recent signs of a change, perhaps allowing him an interim role until a new government is formed.

On Friday, a Russian diplomat raised the possibility of Moscow joining the Washington-led coalition against ISIS provided the U.N. Security Council gave a legal framework for its action.

“It is in theory possible that all those involved join the coalition if it receives the approval of the U.N. Security Council,” Ilya Rogatchev, head of the Russian Foreign Ministry’s Department for New Challenges and Threats, told AFP.