Turkey vowed to press ahead with its offensive in northern Syria on Tuesday despite US sanctions and growing calls for it to stop, while Syria’s Russia-backed army moved on the key city of Manbij that was abandoned by US forces.br br US President Donald Trump’s unexpected decision to withhold protection from Syria’s Kurds, after a phone call with Erdogan (below) a week ago, swiftly upended five years of US policy on Syria.br br As well as clearing the way for the Turkish incursion, the US withdrawal gives a free hand to Washington’s adversaries in the world’s deadliest ongoing war, namely Syrian President Bashar al-Assad and his Russian and Iranian allies.