President Vladimir Putin warned the West against taking one-sided action in Syria but also said Russia "doesn't exclude" supporting a UN resolution on punitive military strikes if it is proved that Damascus used poison gas on its own people.
In a wide-ranging interview with the Associated Press and Russia's state Channel 1 television, Putin said Moscow has provided some components of the S-300 air defense missile system to Syria but has frozen further shipments.
He suggested that Russia may sell the potent missile systems elsewhere if Western nations attack Syria without UN Security Council backing.
The interview comes ahead of the summit of G-20 nations in St. Petersburg, which opens tomorrow. The summit was supposed to concentrate on the global economy but now looks likely to be dominated by the international crisis over allegations that the Syrian government used chemical weapons in the country's civil war.
Putin said he felt sorry that President Barack Obama canceled a one-on-one meeting in Moscow that was supposed to have happened before the summit. But he expressed hope the two would have serious discussions about Syria and other issues.
"President Obama hasn't been elected by the American people in order to be pleasant to Russia. And your humble servant hasn't been elected by the people of Russia to be pleasant to someone either," he said of their relationship.
Putin said it was "ludicrous" that the government of President Bashar Assad - a staunch ally of Russia - would use chemical weapons at a time when it was holding sway against the rebels.
"From our viewpoint, it seems absolutely absurd that the armed forces, the regular armed forces, which are on the offensive today and in some areas have encircled the so-called rebels and are finishing them off, that in these conditions they would start using forbidden chemical weapons while realizing quite well that it could serve as a pretext for applying sanctions against them, including the use