Russia said that the effectiveness of the U.S. mission against Islamic State group in Syria is "insignificant."

Russian Foreign Minister Sergey Lavrov questions the sincerity of the U.S.’ campaign against ISIS, and believes that the U.S.-led coalition may be more interested in changing the regime.

"We have very few specifics which could explain what the US is exactly doing in Syria and why the results of so many combat sorties are so insignificant," Lavrov told Russian channel NTV. "With, as far as I know, 25,000 sorties they (the US-led air campaign) could have smashed entire Syria to smithereens."

The Russian minister expressed concern about U.S. forces airdropping weapons for "moderate" Syrian rebels. "I want to be honest; we barely have any doubt that at least a considerable part of these weapons will fall into the terrorists’ hands," Lavrov said.

Meanwhile, Russia is expected to hold talks with the U.S. on air safety in Syria. The talks have been scheduled as combat aircraft from both nations recently came dangerously close against each other.

Even though U.S. authorities are going to hold talks with Russia on the issue for the third round now, they have said Russia’s actions in Syria are "wrongheaded," the BBC reported. Russia started its air campaign in Syria in September. Kremlin claimed that the campaign, a result of Syrian President Bashar Assad seeking military help from Russia, would target ISIS militants.

Western authorities, on the contrary, claim that Russia is working on behalf of Assad and focusing on non-militant targets. While Moscow has been candid about its support for Assad, it has denied claims that its operation comes with hidden agenda.