Kremlin spokesperson Dmitry Peskov warned Wednesday that "a whole series of nuances" needs to be addressed before Russia will agree to any U.S.-brokered peace deal.

A senior Kremlin official says clinching a deal to end the war between Russia and Ukraine “is far too complex to be done quickly.”

President Vladimir Putin is open to peace in Ukraine and intense work is going on with the United States, but the conflict is so complicated that the rapid progress which Washington wants is difficult to achieve,

Russian forces have significantly increased the intensity of their combat activity in eastern Ukraine, Ukraine's top military commander Oleksandr Syrskyi said on Wednesday. Russian President Vladimir Putin has declared a three-day ceasefire from May 8-10 to mark the 80th anniversary of the victory of the Soviet Union and its allies in World War Two.

The Kremlin said on Tuesday that Ukraine had not responded to many offers by Russia President Vladimir Putin to start direct peace negotiations.