Russia says its forces will halt fire around Aleppo for three hours daily to allow humanitarian aid into the ravaged Syrian city.
Senior Defense Ministry official Sergei Rudskoi said that "all military action," including air and artillery strikes, would be halted from 10 a.m. to 1 p.m. local time starting on August 11.
UN humanitarian affairs chief Stephen O'Brien said pauses for at least 48 hours would be needed to allow time for aid to be loaded onto trucks and delivered to the city and for evacuations to take place.
"We would welcome any pause that successfully facilitates delivering vitally needed humanitarian supplies, but such a cease-fire must be observed by all parties," the U.S. State Department said.
Russia's announcement comes after the United Nations called for an immediate pause in fighting in Aleppo to allow the water and electricity networks to be fixed.
Some 2 million people are without vital supplies around Aleppo, according to the UN.
Rudskoi also said some 7,000 militants with artillery, tanks, and other armed vehicles had been massing southwest of Aleppo for the past week and were still being joined by new fighters.
Fighting between government forces and rebels has intensified around Aleppo in recent weeks.