LONDON, April 10- British Prime Minister Theresa May spoke on Monday to US President Donald Trump and agreed that "a window of opportunity" now exists to persuade Russia to break ties with Syrian President Bashar al-Assad, May's office said.
A spokeswoman for the prime minister said Trump had thanked May for her support following last week's US military action in Syria against the Assad regime.
In a shift in Washington's strategy, US missiles hit a Syrian air base last week in retaliation for what the United States and its allies say was a poison gas attack by Syria's military in which scores of civilians died. The Syrian government has denied it was behind the assault.
Trump had previously appeared disinclined to intervene against the Syrian leader and the attack raised expectations that he might now be ready to adopt a tougher-than-expected stance with Russia, Assad's main backer.