G7 foreign ministers are trying to agree on a standard position for the Syrian conflict, ahead of the US secretary of state flying to Russia to try and persuade it to abandon its Syrian ally.
Rex Tillerson will likely meet officials from allied Middle Eastern countries before going to Moscow.
Great Britain has suggested tightly-focused sanctions on Russian and Syrian military officers.
The moves continue with apparent use of chemical weapons in Syria.
Syria has denied attacking the rebel-held area of Khan Sheikhoun last week that left 89 people dead.
The Associated Press news agency quoted a senior US official as saying that the Russians knew of the chemical attack while drones have been flying over a hospital in Khan Sheikhoun spotted victims solooking for help. Hours later a jet bombed a healthcare facility of what the usa believed was an endeavor to conceal the attack, the company said.
In reply, the USA says it destroyed a fifth of Syria’s operational aircraft within an air strike fat the Shayrat airbase last Thursday and said further strikes could take place.
Why was Shayrat airbase bombed?
Decoding Russia’s a reaction to Johnson’s cancelled trip
President Trump and UK Pm May said during an unscheduled visit that it was not in Russia’s strategic interest to support President Assad.
German Chancellor Angela Merkel meanwhile agreed with President Trump that President Assad needs to be held accountable for his actions, the White House said.