UPDATE: 7:56 a.m. EDT — Russia said Sunday that it was in talks with Syria to include Aleppo in the regions where fighting could be stopped, Reuters reported citing Russian media. Fighting had continued in Aleppo despite the Syrian army declaring a “regime of calm” late Friday, applicable to some regions in the country.

The reports from Russia cited General Sergei Kuralenko, the head of Russia's ceasefire monitoring centre in Syria, who said: “At present, there is an active negotiation process taking place to establish a regime of calm also in Aleppo province.”

Original story:

The United States is working on initiatives to end the escalating violence and bloodshed in the war-torn Syria, according to media reports late Saturday. The news comes amid days of deadly bombardments in the city of Aleppo, which has witnessed the worst fighting in the 5-year-old conflict that has killed more than 270,000 people and displaced millions.

The U.S. government reportedly wants Russia to put pressure on the Syrian government to stop "indiscriminate aerial attacks" in Aleppo, where more than 200 people died in the last week of April. U.S. Secretary of State John Kerry made several calls over the past two days to the United Nations Special Envoy for Syria, Staffan de Mistura, and Riad Hijab, chief coordinator of High Negotiations Committee, the main opposition bloc in Syria, to end the violence. 

Kerry expressed "deep concern" about Aleppo during the calls to de Mistura and Hijab, U.S. State Department spokesman John Kirby said Saturday. "The secretary made clear that ending the violence in Aleppo and returning ultimately to a durable, nationwide cessation is a top priority."

The surge in fighting in Aleppo has led to the collapse of a two-month ceasefire which was brokered by the U.S. and Russia. Moscow has said the airstrikes on Aleppo target terrorist groups.

However, during the calls, Kerry dismissed the Russian claim that the Aleppo strikes were targeting the Al-Nusra Front, a jihadist group not party to the ceasefire. A new round of U.N.-backed peace talks is set to start on May 10 in Geneva, according to BBC.

"The secretary made clear that we urged Russia to take steps to stop regime violations, especially its indiscriminate aerial attacks in Aleppo," Kirby said. "The Assad regime continues to escalate the conflict by predominantly targeting innocent civilians and parties to the cessation of hostilities — not Nusra, as the regime falsely claims. Such attacks are direct violations of the cessation and must stop immediately."

Russia entered the conflict at the end of September 2015 when it began airstrikes, but faced criticism from Western officials who claimed that the Kremlin targeted opposition groups to help longtime ally Syrian President Bashar Assad remain in power.