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,

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.

Russian President Vladimir Putin announced Monday a three-day cease-fire in its war with Ukraine is set to take place in May, but Ukrainian officials question its timing and validity.