Clinton and Lavrov set for showdown over Syria transition plan Assad also said any future government in Syria must hold free and fair elections for a multiparty government. Russia is Syria's most important ally, protector and supplier of arms. Diplomatic hopes for have rested on persuading Russia to agree to a plan that would end the Assad family dynasty, which has ruled Syria for more than four decades. The difference in interpretation between the U.S. and Russia could prove to be the plan's unraveling. Clinton hopes to press Lavrov on the point at their meeting and over dinner following a gathering of Asia-Pacific foreign ministers that Lavrov is hosting in St. Petersburg. On Thursday, Lavrov acknowledged that a transition period is necessary to end the violence in Syria, but said Russia had not agreed to all elements of Annan's plan, in particular any suggestion that Assad would be required to leave. "We are not supporting and will not support any external meddling," Lavrov said. External players must not dictate ... to Syrians, but, first of all, must commit to influencing all the sides in Syria to stop the violence. He also said the Annan plan was still a work in progress. But, Clinton, speaking Thursday in Riga, Latvia, said it was "very clear" that all participants in the Geneva meeting, including Russia, were on board with the transition plan. She told reporters that the invitations made clear that representatives "were coming on the basis of (Annan's) transition plan." She said she expects the meeting "to provide an opportunity to make real progress" on that plan.