"We have made substantial movement forward," Lavrov said at a joint press conference with US Secretary of State Hillary Clinton, referring to talks on replacing the 1991 Strategic Arms Reduction Treaty (START).
START, which places strict limits on the US and Russian arsenals and is seen as a cornerstone of strategic arms control, expires on December 5.
US and Russian negotiators have been seeking to thrash out a successor agreement by the treaty's expiration date.