Russia has warned the US it will start responding to ceasefire violations in Syria unilaterally from Tuesday if the US refuses to co-ordinate the rules of engagement against the violators.
The Russian military has accused the US of dragging its feet on responding to Moscow's proposals on joint monitoring of a Syria ceasefire.
A top Russian general said on the weekend that further delays were leading to civilian casualties, such as in Aleppo where 67 civilians have reportedly 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 because the US, in talks with Russia last week, had refused to co-ordinate a joint response.
"The American side was not ready for this particular discussion and for the approval of the agreement," the statement quoted him as saying.
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There was no immediate reaction from US officials.
The Russian- and US-brokered ceasefire that began on February 27 has helped significantly reduce hostilities. The Islamic State group and the al-Qaeda-linked Nusra Front have been excluded from the truce.
Russian President Vladimir Putin last week recalled some Russian warplanes from Syria, but said the action against IS and the Nusra Front will continue.
