Russia knew in advance that Syria was planning a chemical weapons attack on its own people but did nothing to prevent it, the US has concluded.
A senior US official told AP that Washington had analysed reports of a drone flying over the site, and determined that the drone was operated by the Russians.
The drone went up immediately after the April 4 sarin gas attack, and begun hovering over a local hospital as victims began pouring in. Five hours after the sarin attack, the camera switched off and a Russian-made aircraft struck the hospital. The two military officials said that it was unclear whether the aircraft were Russian or Syrian as the Syrians buy Russian-made aircraft.
US officials believe the jet bombed the hospital in an attempt to cover up the usage of chemical weapons.
The official said it still was not clear who was flying the jet that bombed the hospital. But official said the presence of the drone could not have been a coincidence, and that Russia must have known the chemical weapons attack was coming and that victims were seeking treatment. The official believed the drone was positioned near the town to assist with the aftermath.
The revelation dramatically ratchets up the tension for the meeting between Rex Tillerson, the US secretary of state, and his Russian counterpart Sergei Lavrov. Mr Tillerson arrives in Moscow on Tuesday.
On Sunday he said that he was yet to see any evidence of Russian involvement in the gas attack, despite there being up to 100 Russian servicemen on the air field from where the gas-carrying planes took off.
“I've not seen any hard evidence that connects the Russians directly to the planning or execution of this particular chemical weapons attack,” he said. “And, indeed, that's why we've tried to be very clear that the Russians were never targeted in this strike.”
He was asked what would happen if America then determined that the Russians were responsible.
“Well, that is going to be clearly very damaging to US-Russian relations,” he replied.
Russia is yet to respond to the US conclusions about the sarin attack, but has described the subsequent air strikes as “an act of aggression”.