BEIRUT (AP) — When Russian Foreign Minister Sergei Lavrov said his country was ready to aid Syrian rebels fighting the Islamic State group, rebel commanders scoffed, pointing out that Russian aircraft were pounding their bases in central and northern Syria on a daily basis. [...] Lavrov not long ago had ridiculed the main Western-backed rebels known as the Free Syrian Army, calling the group a "phantom structure." [...] some in the Syrian opposition are wondering whether the Russian offer, for all its ambiguity, might be worth seizing in order to test Moscow's commitment to finding a negotiated solution to the four-year civil war. Russia says it has already met with rebel commanders in Moscow, a claim denied by the opposition and their political allies. Russia is signaling that it is willing to include rebel fighters in any unified Syrian military force to fight terrorism that might emerge from negotiations, Jaber said. In a sign of possible discord with his Russian allies, Assad's office issued a statement Tuesday reiterating that he will not consider any political initiatives "until after eradicating terrorism." The statement was in response to comments by Russian lawmakers who visited Assad on Sunday and said the Syrian leader was willing to hold early presidential elections that he would run in.