US President Donald Trump and British Prime Minister Theresa May say a "window of opportunity" exists to convince Russia to stop backing Syrian President Bashar al-Assad.
According to a Downing Street spokeswoman, the agreement was made following a phone conversation between May and Trump in relation to a chemical attack in Syria.
"The prime minister and the president agreed that a window of opportunity now exists in which to persuade Russia that its alliance with Assad is no longer in its strategic interest," she said.
She added that the conversation "provides an opportunity to make progress towards a solution which will deliver a lasting political settlement."
The call was initiated on the eve of a scheduled trip by US Secretary of State Rex Tillerson to Russia.
Trump also engaged in a phone conversation with German Chancellor Angela Merkel in which they agreed on holding Syria responsible for the chemical attack.
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On Friday, US President Donald Trump ordered the military to carry out a barrage of missile strikes against a Syrian airfield. He claimed that operation was in response to a suspected chemical attack, which Washington insists was carried out by Syrian fighter jets operating from the base.
Britain has announced that it "fully supported" the US attack, and British Foreign Minister Boris Johnson canceled a visit to Moscow citing fundamental developments in Syria.
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Syria has categorically denied carrying out the gas attack, with the foreign minister stressing that an Idlib airstrike had targeted a depot, where terrorists stored chemical weapons.