Any U.S. military action taken in response to apparent chemical weapons attacks in Syria would need to be approved by the U.N. Security Council, international envoy Lakhdar Brahimi said on Wednesday.
"I think international law is clear on this. International law says that military action must be taken after a decision by the Security Council. That is what international law says," he told a press conference in Geneva.
"I must say that I do know that President Obama and the American administration are not known to be trigger-happy. What they will decide I don't know. But certainly international law is very clear."
In a telephone call on Tuesday, Russian Foreign Minister Sergei Lavrov told Brahimi that "attempts at a military solution will lead only to the further destabilisation of the situation in [Syria] and the region," a ministry statement said.
The United States and its allies are gearing up for a probable military strike to punish President Bashar al-Assad, whom they blame for a alleged chemical attack last week that activists said killed hundreds of people as they slept.
U.N. Security Council member Russia, a major arms supplier to Assad and his most powerful diplomatic ally in the conflict, says rebels may have carried out the gas attack to provoke outside military intervention.
In a separate phone conversation on Tuesday, Lavrov rejected U.S. Secretary of State John Kerry's assertion that the government was to blame.
Lavrov called for a "detailed and in-depth exchange of information" on all alleged use of chemical arms.
