LONDON, Oct 11 (Reuters) - Russian Foreign Minister Sergei Lavrov said on Tuesday that the United States had long been involved in the war in Ukraine."It seems to me that the Americans have been participating de facto in this war for a long time," Lavrov told Russian state television.Lavrov said that officials including White House national security spokesman John Kirby had said the United States was open to talks but that Russia had refused."We have not received any serious offers to make contact."Register now for FREE unlimited access to Reuters.comOur Standards: The Thomson Reuters Trust Principles."