DAMASCUS – By refusing to clarify the scale of its military presence in Syria, Russia keeps the West fearing a considerable build-up to win a stronger bargaining position when world powers sit down to talks on the conflict, Western diplomats in Moscow said.

Those discussions could take place as soon as this month, when Russian President Vladimir Putin comes to the United States for the first time in some eight years, to speak at the annual United Nations General Assembly.

Russia’s central demand now is that its long-time ally, Syrian President Bashar al-Assad, should be included in international efforts to contain ISIS and control large tracts of Syria.

U.S. officials said on Wednesday Russia had sent two tank landing ships and additional aircraft to Syria and deployed a small number of forces there.

In Lebanon, sources said Russian forces are taking part in combat in Syria, where Assad has come under increasing pressure.

“It’s all about the General Assembly,” said one of the diplomats, who like other sources spoke on condition of anonymity.

“If there is a real new start in dialogue between Russia and the United States – we have a whole new situation, new quality.”

Moscow has signaled several times in recent weeks it is interested in a meeting between Putin and President Obama in New York. The White House says it is not aware of any meeting planned at the moment.

Washington expressed concern over the Russian military build-up in Syria and put pressure on countries nearby to deny their air space to Russian flights to the country.

Russia has decried the U.S. pressure over the flights as “international boorishness” and dismissed reports of a build-up in Syria in general terms.

But Russian officials have repeatedly dodged questions over whether there has been a recent increase in military assistance to Assad and Moscow has not unequivocally denied any build-up of its forces in Syria.