Speaking alongside his French counterpart at the State Department, Kerry said Russia should be held accountable for what he called a "siege of innocent people."
“Russia and the [Bashar al-Assad] regime owe the world more than an explanation about why they keep hitting hospitals and medical facilities and children and women," Kerry said.
"These are acts that beg for an appropriate investigation of war crimes and those who commit these would and should be held accountable for these actions. They are beyond the accidental. ... This is a targeted strategy to terrorize civilians and to kill anybody and everybody who is in the way of their military objectives," Kerry added.
The International Criminal Court in the Hague is the organization that would oversee a war crimes investigation if there were one. But any investigation would have to be approved by the United Nations Security Council and Russia has veto power within that body.
The past two weeks have seen a brutal onslaught of rebel-held parts of Aleppo by the Russian-backed Syrian regime. Bombings intensified to new levels after a failed attempt at a cease-fire over two weeks ago. In that time, human rights groups have counted hundreds of civilian deaths in Aleppo.
The U.S., which supports moderate opposition groups, said earlier this week that it had abandoned diplomatic talks with Russia to resolve the crisis. In turn, Russia warned the United States not to attack regime military positions, perceived in Washington as a threat of force.