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.
Hours later a jet bombed the hospital in what the US believed was an attempt to cover up the attack, the agency said. In response, the US says it destroyed a fifth of Syria’s operational aircraft in an air strike on the Shayrat airbase last Thursday and said further strikes could take place.
Trump and UK Prime Minister Theresa May said during a phone call that it was no longer in Russia’s strategic interest to support Syrian President Bashar al-Assad.
German Chancellor Angela Merkel meanwhile agreed with Trump that President Assad should be held accountable, the White House said.