Vladimir Putin has dismissed as "utter nonsense" America's claim that the Syrian regime used chemical weapons against its own people - a claim which has proved crucial in the push for outside intervention in the country's brutal civil war.
The Russian President also called on the Obama administration to present the evidence behind its claims to the UN Security Council.
Yesterday the US Secretary of State, John Kerry, accused pro-Assad forces of killing 1,429 people - including 426 children - with chemical weapons in a Damascus suburb on 21 August. He called the attack an "inconceivable horror".
President Barack Obama said the US was considering a "limited narrow act," based on the intelligence.
The Assad regime said the Kerry statement was "full of lies", claiming opposition fighters launched the attack.
And today the regime was boosted by Putin, who told journalists in Vladivostok: "Syrian government troops are on the offensive and have surrounded the opposition in several regions.
"In these conditions, to give a trump card to those who are calling for a military intervention is utter nonsense."
A key Syria ally on the Security Council, Putin has previously warned that "any unilateral military action bypassing the UN Security Council" would be a "direct violation of international law".
The conflict, now in its third year, is fought between the regime and anti-government rebels, mostly from the disparate Free Syrian Army. It has spilled periodically across Syria's borders with Lebanon, Iraq and Turkey, threatening to engulf the region. It has made almost two million refugees and last month the UN Secretary General Ban Ki-Moon said it has claimed more than 100,000 lives.
On Thursday in the UK, MPs debated military intervention, with Prime Minister David Cameron claiming evidence suggests President Assad did use chemical weapons against his own people. Cameron's motion for possible military action was defeated by 285-272, with a strong rebellion by his own MPs and some ministers.