The UN Security Council will vote late tonight on a US-drafted resolution that would extend for a year an international probe to determine who is behind chemical attacks in Syria's six-year war.<br/><br/>The United States and Russia, Syria's ally, have put forward rival draft resolutions on renewing the mandate of the Joint Investigative Mechanism (JIM), tasked with investigating Syria's toxic gas attacks. The vote is scheduled just hours before the mandate of the so-called JIM expires.<br/><br/>It remained unclear whether Russia would veto the US- drafted measure, which would be the 10th time that Moscow has used its veto power at the council to block action targeting its Syrian ally.