Russia has warned it may take unilateral action against violations of the cease-fire agreement in Syria, accusing the United States of failing to develop plans to enforce the agreement and punish violations.

“The Russian military have accused the U.S. of dragging its feet on responding to Moscow’s proposals on joint monitoring of a Syria cease-fire,” reports the Associated Press. “A top Russian general said on the weekend that further delays are leading to civilian casualties, like in Aleppo where 67 civilians reportedly have been killed by militant fire since the truce started.”

“Lt. Gen. Sergei Rudskoi of the Russian General Staff said in a statement on Monday that Russia will have to use force unilaterally that because the U.S., in talks with Russia last week, had refused to coordinate a joint response,” the report continued.

U.S. officials responded by insisting the Russians were “misinformed,” and issues pertaining to the cease-fire agreement “continue to be discussed in a constructive manner.”

CBS News describes the Russian warning as an “ultimatum,” with the Russians potentially beginning unilateral strikes against cease-fire violators as early as tomorrow.

“Both sides have complained continually of cease-fire violations since the day it took effect, with moderate opposition groups claiming the Assad regime has continued attacking them, also,” CBS reports.

According to the Wall Street JournalLt. General Rudskoi stipulated that Russia would only use military force “after receiving reliable proof of systemic violations.”

It should be noted these violation complaints do not refer to hostilities from the Islamic State or al-Qaeda’s Nusra Front, as both were excluded from the cessation-of-hostilities agreement.

Reuters says the U.S. has rejected a Russian call for an urgent meeting over cease-fire violations.