The head of the UN observer mission in Syria has said he was frustrated with the failure to reduce the violence and end the government's use of heavy weapons.<br /><br />Lieutenant General Babacar Gaye was giving his final news conference in Damascus ahead of the end of the mission on Sunday.<br /><br />The observers' departure follows the UN Security Council's decision to end the mission and replace it with a small liaison office. <br /><br />The expiry of the observers' mandate represents a serious blow to international efforts to end the conflict.<br /><br />Al Jazeera's Scott Heidler, reporting from the UN headquarters in New York, assesses what the mission achieved and what future role the UN can now play.
