US Secretary of State Rex Tillerson has said he is "disappointed" in but not surprised by Russia's criticism of the US airstrikes on a Syrian airfield as an "act of aggression".
Mr Tillerson, who is scheduled to visit Moscow next week, was questioned on Russia's comments during a White House media briefing.
"I'm disappointed in (the Russian) response," he said. "Because it indicates their continued support for the Assad regime and, in particular, their continued support for a regime that carries out these type of horrendous attacks on their own people.
"So I find it very disappointing, but, sadly, I have to tell you, not all that surprising."
Russia's foreign ministry has said it expects Mr Tillerson to explain Washington's stance on the airstrikes during his visit, according to the Interfax news agency.
Boris Johnson looks "daft" and is in "deep political trouble" after pulling out of a meeting with the Russians, Alex Salmond has said.
The defence secretary condemned Vladimir Putin's Kremlin for its role in Bashar Assad's suspected chemical weapons attack on his own people.
The leading critic of the Trump administration has told ITV News the US and its allies must build on the president's justified airstrikes.