After months of deliberation, President Barack Obama's administration said on Thursday it would now arm rebels, having obtained proof the Syrian government used chemical weapons against fighters trying to overthrow President Bashar al-Assad.
He added that the evidence put forth by the US of chemical weapons use in Syria does not meet stringent criteria for reliability. Mr Lavrov said that for the samples to be conclusive, they would have to have been supervised by experts from the moment they were retrieved to the moment they entered the laboratory.
Mr Lavrov's comments will pour cold water on any hopes of reaching a multinational agreement about how to deal with the war in Syria.
David Cameron said on Friday that he supported the Americans' decision.
"I welcome this candid assessment by the Americans," he said on Friday.
"I think it, rightly, puts back centre stage the question, the very difficult question to answer but nonetheless one we have got to address: what are we going to do about the fact that in our world today there is a dictatorial and brutal leader who is using chemical weapons under our noses against his own people."
He added that the evidence put forth by the US of chemical weapons use in Syria does not meet stringent criteria for reliability. Mr Lavrov said that for the samples to be conclusive, they would have to have been supervised by experts from the moment they were retrieved to the moment they entered the laboratory.
Mr Lavrov's comments will pour cold water on any hopes of reaching a multinational agreement about how to deal with the war in Syria.
David Cameron said on Friday that he supported the Americans' decision.
"I welcome this candid assessment by the Americans," he said on Friday.
"I think it, rightly, puts back centre stage the question, the very difficult question to answer but nonetheless one we have got to address: what are we going to do about the fact that in our world today there is a dictatorial and brutal leader who is using chemical weapons under our noses against his own people."