Russian President Vladimir Putin on Saturday dismissed as “nonsense” claims that the Syrian regime has used chemical weapons and demanded that the United States provide proof.

Speaking after the United States released an intelligence report, Putin rejected US intercepts of Syrian communications as evidence, saying that they cannot be used to take “fundamental decisions” like using military force on Syria.

“Common sense speaks for itself,” Putin told journalists in Vladivostok when asked about claims that the Syrian Army used chemical weapons last week.

“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.”

Putin said he is sure that the attack is “nothing but a provocation” by those who want to drag other countries into the Syrian conflict and demanded to be proved otherwise.

“Regarding the position of our American colleagues, friends, who affirm that government troops used weapons of mass destruction, in this case chemical weapons, and say that they have proof, well, let them show it to the United Nations inspectors and the Security Council,” Putin said.

Saying that such evidence is classified “does not stand up to criticism,” Putin said. “It’s outward disrespect toward partners and world actors. If there is evidence, it must be presented. If they don’t show it, that means there is none.”

“Talk that these are once again some kind of intercepts of some kind of communications that don’t prove anything cannot be used as a basis for such fundamental decisions like using force against a sovereign state,” Putin said.

It was Putin’s first public reaction to the US claims that the Syrian government had used chemical weapons in the suburbs of Damascus on August 21, killing 1,429 people.

The remarks follow a US intelligence report regarding the killings and remarks by US President Barack Obama that the attack is “a challenge to the world.”

The Russian foreign ministry said on Saturday that the US ambassador to Moscow, Michael McFaul, met with deputy foreign minister Sergei Ryabkov to present the US case against Syria.

Ryabkov warned the US envoy that any use of force would be “an act of aggression,” according to a ministry statement.

Russia had also welcomed Friday’s rejection by the British parliament of military action against the Syrian regime.

“Over the last few years, everyone, including me, has gotten used to the western community deciding things without much discussion... And according to the wishes and position of the main partner, the United States," Ryabkov said.

“If this time there is some kind of glitch, to me that is unexpected, and I am actually surprised by this position. On the other hand that shows that even in Britain, although it’s the main geopolitical ally of the US... There are people that rely on national interests and common sense and value their sovereignty.”

Russia, Syria’s vocal and powerful ally, has vowed to block any action against the regime of Syria’s Bashar al-Assad in the UN Security Council, where it is a permanent member.