Pressure is mounting on Russia to work with the international community in determining which groups in Syria to attack -- and which, instead, deserve a seat at talks on a peaceful future for the country.
U.S. Secretary of State John Kerry said Saturday that Russia's attacks in Syria have been largely "against legitimate opposition groups" and that it was critical for the country's method of targeting to change.
The entire International Syria Support Group, including Russia, "has agreed to work to make that happen," Kerry said. "There is no way to adequately deal with the cessation of hostilities unless we do sit down and work together on every aspect of this."
Groups who are being bombed, Kerry said, will be disinclined to talk. He made his comments an address to the Munich Security Conference on Saturday.
This week, major world powers agreed to a "cessation of hostilities" in Syria and to the delivery of immediate aid. But Kerry said Saturday that much work remained to be done before peace would become a reality.
The civil war in Syria has raged for five years, destroying once-great cities, killing nearly a half-million people, and setting several million to flight in a historic migratory wave that Kerry acknowledged Saturday was fraying the social fabric of Europe.
Russia denies air attacks on Syrian civilians
For its part, Russia denied Saturday that it is bombing civilians in Syria, insisting instead that it is protecting itself from militants.
"There is no evidence of our bombarding civilians even though everyone is accusing us," Prime Minister Dmitry Medvedev told the conference.
Medvedev defended Russia's military action in Syria, saying it was aimed at protecting national interests and quashing militants.
His comments came after his French counterpart, Manuel Valls, warned Moscow that to achieve peace in Syria, it had to stop bombing civilians.
"We need to have peace, we need to have negotiations, and for that, we need to stop bombings against civilians," Valls said during his speech in Munich.
Russia has carried out airstrikes in support of Syrian government forces battling for Aleppo.
War of words
As battles rage around the embattled Syrian city, so too has the war of words between Russia and the United States.
The defense ministry for Russia turned the tables Thursday with accusations against the United States.
Defense ministry spokesman Igor Konashenkov accused the U.S. of dropping bombs on Aleppo on Wednesday.
This back-and-forth over Syria among outside powers is hardly new. While they claim to have the same military mission -- to combat terrorists, specifically ISIS -- Moscow has been at odds with others over tactics and targets.
The United States and its allies have characterized Russia as a major part of the problem in Aleppo, blaming it for cutting off the city from desperately needed food and aid.