U.S. Secretary of State John Kerry has warned that Washington is considering a "Plan B" to deal with Syria if Damascus and Moscow are not serious about negotiating a political transition.
Testifying before the Senate Foreign Relations Committee on February 23, Kerry said it would be clear very soon whether Russia was serious about ending the five-year conflict.
"The proof will be in the actions that come in the next days," he said.
The comments come as an accord between the United States and Russia to scale back violence in Syria is supposed to start on February 27.
Meanwhile, fighting continued in Syria, with the British-based Syrian Observatory for Human Rights reporting that Islamic State militants have captured the town of Khanaser, cutting a road used to supply government-controlled areas in the northern city of Aleppo.
Based on reporting by AFP, AP, and Reuters