Separately, two US officials said the United States was expected to inform Russian Federation on Thursday it was suspending their diplomatic contacts on Syria given the collapse a jointly brokered truce on September 19 and the latest violence in Aleppo.
According to him, Kerry also made Russian Federation responsible for the use of incendiary and bunker busters in Aleppo, for the offensive of the Syrian government forces in general, the humanitarian situation in the city and the alleged attacks on the civilian infrastructure.
The Russian military has said it is ready to resume contacts with its United States counterparts over the situation in Syria.
Russian Deputy Minister of Foreign Affairs Sergey Ryabkov reacted angrily to U.S. Secretary of State John Kerry's threat Wednesday to end discussions between the two countries if Russia did not end its current operations in Aleppo and uphold the ceasefire.
"We can not interpret this as anything else apart from the current USA administration's de facto support for terrorism", Ryabkov was quoted as saying.
The United States has threatened to halt its diplomacy with Russian Federation over the issue and it said it held Russian Federation accountable for the use of incendiary and bunker-busting bombs on Aleppo - a view a USA official said could open Moscow up to charges of war crimes. "Not only did the intensity of shelling of government forces positions fail to subside, but the armed groups' activity increased", Poznikhir said, RT reported. More than 250 people are believed to have been killed in the besieged city in the last week. Attacks on water installations from both sides have left more than two million civilians without water.
Washington has been working with Moscow for months to try to secure a cease-fire in Syria.
Russian Federation would agree to a 48-hour ceasefire in Syria's Aleppo city, but would not allow it to be extended for a week, said a top official on Thursday.
Now, another official said, the administration once again finds itself forced to respond to a Russian initiative, as it did in Ukraine and Crimea and also is doing in cyberspace.
On Wednesday, Kerry called his Russian counterpart Sergei Lavrov to warn that he would end talks unless Moscow halts the assault on Aleppo and forces Bashar al-Assad to ground the Syrian air force. When journalists asked about possible consequences should Russian Federation continue its military actions in Syria, Kirby stated that the civil war in Syria would continue. Jaafari walked away laughing without an answer. "They know they are committing war crimes", he said.
People walk on the rubble of damaged buildings after an airstrike in the opposition held area of Aleppo's Baedeen district, Syria, May 3, 2016.
"The civilians there would seize any opportunity to escape, to go wherever they could go", Raed Saleh told AFP news agency.