Russian Prime Minister Vladimir Putin has accused the US of orchestrating the conflict in Georgia, possibly for domestic election purposes.
Mr Putin told CNN US citizens were "in the area" during the conflict over South Ossetia and were "taking direct orders from their leaders".
He said his defence officials had told him this was to benefit one of the US presidential candidates.
The White House dismissed the allegations as "not rational".
Georgia tried to retake the Russian-backed separatist region of South Ossetia this month by force after a series of clashes.
Russian forces subsequently launched a counter-attack and the conflict ended with the ejection of Georgian troops from both South Ossetia and another rebel region, Abkhazia, and an EU-brokered ceasefire.
Mr Putin said in the interview: "The fact is that US citizens were indeed in the area in conflict during the hostilities.
"It should be admitted that they would do so only following direct orders from their leaders."
Mr Putin added: "The American side in effect armed and trained the Georgian army.
"Why... seek a difficult compromise solution in the peacekeeping process? It is easier to arm one of the sides and provoke it into killing another side. And the job is done.
"The suspicion arises that someone in the United States especially created this conflict with the aim of making the situation more tense and creating a competitive advantage for one of the candidates fighting for the post of US president."
White House spokeswoman Dana Perino rejected the allegation.
"To suggest that the United States orchestrated this on behalf of a political candidate - it sounds not rational," she said.
"Those claims first and foremost are patently false, but it also sounds like his defence officials who said they believed this to be true are giving him really bad advice."
Diplomatic wrangling over Russia's actions in Georgia continued on Thursday with French Foreign Minister Bernard Kouchner suggesting some EU countries were considering sanctions.
Mr Kouchner insisted France had made no proposals for sanctions itself but, as current president of the EU, would aim to get consensus among all 27 countries of the bloc if sanctions were envisaged.
Russian Foreign Minister Sergei Lavrov described talk of sanctions as the working of "a sick imagination".
Such talk was an emotional response that demonstrated Western confusion over the situation, he said.
The US has said it is now considering scrapping a US-Russia civilian nuclear co-operation pact in response to the conflict.
"I don't think there's anything to announce yet, but I know that that is under discussion," Mr Perino said.
The White House has also announced that up to $5.75m (£3.1m) will be freed to help Georgia meet "unexpected and urgent refugee and migration needs".