"It [violence] also poses a risk to Russia back home because we know that this kind of violence and chaos…only fuels extremism in Syria and around the world," Earnest said in a briefing.
The Russian authorities, Earnest claimed, will have to invest additional resources in their efforts in Syria as the country draws itself deeper into the sectarian conflict.
"Russia will have to account for their actions in the context of the consequences they are likely to provoke," Earnest stated.
Russia launched airstrikes against terrorist positions in Syria on September 30, 2015 at the request of President Assad. Russian military aviation had conducted more than 9,000 sorties until March 2016, helping Damascus turn the tide of war and launch offensives in key regions of the country.
In March, Russian President Vladimir Putin made a decision to withdraw much of the Russian forces from Syria after determining they successfully fulfilled their tasks there.