Russia has rejected US calls to halt the bombardment of Aleppo, the besieged northern Syrian city, vowing to continue its "struggle with terrorists" alongside government forces.
Dmitry Peskov, the Kremlin's spokesman, described the US threat to end co-operation on a ceasefire agreement if the bombing of Aleppo did not stop as "somewhat awkward".
The rhetoric is a sign of the rising tension between Moscow and Washington over the Syrian conflict.
A ceasefire brokered by Washington and Moscow two weeks ago collapsed when the Syrian regime launched one of the fiercest bombing campaigns of the five-year war on Aleppo, killing hundreds of people. The offensive has been backed by Russian fighter jets, with western powers accusing Russia of being an accomplice to war crimes.
John Kerry, the US secretary of state, called on Moscow on Wednesday to take "immediate steps" to end the bombing, hours after the two main hospitals in rebel-held areas of the city were forced to shut after being hit by air strikes.
Sergei Ryabkov, Russia's deputy foreign minister, said Moscow had suggested a 48-hour halt in fighting, only to be rebuffed by the US.
He added that Washington’s calls for a seven-day break in hostilities would allow “terrorist groups to do everything necessary to restock their supplies, rest their fighters and regroup their forces”.
Moscow accuses the US of failing to uphold its obligations under the agreement to decouple Syria's armed opposition groups that are backed by Washington from Jabhat Fateh al-Sham, which was an offshoot of al-Qaeda. The jihadi group, which was formerly known as Jabhat al-Nusra and is designated as a terrorist organisation by Washington, is one of the most effective militant groups fighting in Syria.
Igor Konashenkov, Russia's defence ministry spokesman, said the "opposition supposedly waging civil war in Syria is a global terrorist 'international [Group]' under control of the US".
Critical battleground
Aleppo, which is divided between rebel and government forces, has become the critical battleground in the war. President Bashar al-Assad’s forces launched a ground offensive on Tuesday in an attempt to retake the city’s rebel-held east, where some 250,000 people are trapped.
Rebel groups say they have lost territory to regime forces around the Handarat base north of the city and close to one of the main routes into Aleppo, where Assad forces are working to solidify their siege. But so far the regime has made little progress pushing into the opposition-held districts of the city, despite the air strikes.
Mr Ryabkov said media reports that the Pentagon is considering a military solution to the impasse over Aleppo were proof that the US wanted to undermine the ceasefire agreement.
“We always knew that the Americans were keeping that up their sleeve,” he told the Interfax news agency. “Obviously, there are a lot of extremists among the groups sponsored by the Americans [and] those who don’t see an alternative to a military solution are responding to that signal.”
Copyright The Financial Times Limited 2016