G7 foreign ministers will attempt to agree a common position on the Syrian conflict, before the US secretary of state flies to Russia to try to persuade it to abandon its Syrian ally.
Rex Tillerson will also meet officials from allied Middle Eastern countries before heading to Moscow.
The UK has suggested threatening tightly focused sanctions on Russian and Syrian military officers.
The moves follow the latest apparent use of chemical weapons in Syria.
Syria has denied it carried out a chemical attack on the rebel-held town of Khan Sheikhoun last week that left 89 people dead.
Reports overnight quoted a senior US official as saying that the Russians knew of the chemical attack because a drone had been flying over a hospital in Khan Sheikhoun as victims sought help.
Hours later a jet bombed the hospital in what the US believed was an attempt to cover up the attack, the Associated Press agency said.
Meanwhile, US Defence Secretary James Mattis gave fresh details on the retaliatory strike against Syria’s Shayrat airbase last Thursday.
He said the “measured response” by the US – which saw 59 Cruise missiles fired – had “resulted in the damage or destruction of fuel and ammunition sites, air defence capabilities and 20% of Syria’s operational aircraft”.
The Syrian military admits significant material damage but a Russian defence ministry spokesman said only six Syrian Air Force MiG-23s, plus a number of buildings, were destroyed and that only 23 of the missiles had reached Shayrat.