Britain will support any fresh retaliation by the US for the use of chemical weapons by the Syrian regime of Bashar Assad, Defence Secretary Michael Fallon says.
The White House says it has "potential" evidence the Syrian military is preparing for another chemical attack against rebel forces and has warned the regime will pay a "heavy price" if it goes ahead.
Fallon says Britain backed the US administration of President Donald Trump when it mounted missile strikes against the regime following a chemical attack last April and was prepared to do so again.
"As always in war, the military action you use must be justified, it must be legal, it must proportionate, it must be necessary. In the last case it was," he told the BBC Radio 4 Today program.
"If the Americans take similar action again, I want to be very clear - we will support it."