Clinton responded to a question during a news conference in Helsinki with Finnish Foreign Minister Erkki Tuomioja.
"We have made it clear to the Russians that the outcome they are most concerned about, which would be a sectarian civil war, is made more likely, not less likely, by the international community's failure to take a strong position vis-à-vis the Assad regime," she said. "We disagree on missile defense, but we continue to have expert consultations and look for a way forward that would be mutually acceptable."
Clinton said she believes the Obama administration's efforts to "reset" the U.S.-Russian relationship have been successful overall. But she acknowledged there remain other areas of disagreement, including missile defense systems in eastern Europe.
The secretary praised Finland for its record on human rights, its role in the Syrian conflict and its elimination of barriers for women.