Russia's military is calling for an urgent meeting with U.S. representatives to agree on the mechanism for enforcing the cease-fire in Syria.
"Further delays with implementing the agreed rules of reaction to violations of the cease-fire regime in Syria is unacceptable," the Russian General Staff said in a statement. "Peaceful residents die daily there as a result of provocative actions and shelling."
The statement said Russia would act unilaterally, starting from March 22, if it gets no response.
The cease-fire in Syria began on February 27, helping significantly reduce hostilities.
The Islamic State (IS) group and the Al-Qaeda-linked Al-Nusra Front were excluded from the truce.
Last week, President Vladimir Putin ordered Russian forces to partially withdraw from Syria, but saie action against IS and Al-Nusra Front fighters would continue.
Based on reporting by Reuters, AP, and TASS