UNITED NATIONS — The UN Security Council voted unanimously Friday night to secure and destroy Syria’s chemical weapons stockpile, a landmark decision aimed at taking poison gas off the battlefield in the escalating 2½-year conflict.
The vote after two weeks of intense negotiations marked a major breakthrough in the paralysis that has gripped the council since the Syrian uprising began. Russia and China previously vetoed three Western-backed resolutions pressuring President Bashar Assad’s regime to end the violence.
‘‘Today’s historic resolution is the first hopeful news on Syria in a long time,’’ UN Secretary General Ban Ki-moon told the council after the vote.
Ban stressed, however, that eliminating chemical weapons from the Syrian conflict ‘‘is not a license to kill with conventional weapons.’’
US Secretary of State John Kerry said the ‘‘strong, enforceable, precedent-setting’’ resolution shows that diplomacy can be so powerful ‘‘that it can peacefully defuse the worst weapons of war.’’ Kerry said the destruction of Syria’s chemical weapons stockpile will begin in November and be completed by the middle of next year.
For the first time, the council endorsed the roadmap for a political transition in Syria adopted by key nations in June 2012 and called for an international conference to be convened ‘‘as soon as possible’’ to implement it.
Ban said the target date for a new peace conference in Geneva is mid-November. As a sign of the broad support for the resolution, all 15 council members signed on as cosponsors.
The resolution calls for consequences if Syria fails to comply, but those will depend on the council passing another resolution in the event of noncompliance. That will give Assad ally Russia the means to stop any punishment from being imposed.
Russian Foreign Minister Sergey Lavrov stressed that the resolution does not automatically impose sanctions on Syria.
The vote came just hours after the world’s chemical weapons watchdog adopted a US-Russian plan that lays out timelines for cataloging, quarantining and ultimately destroying Syria’s chemical weapons, their precursors and delivery systems.
The Security Council resolution enshrines the plan approved by Organization for the Prohibition of Chemical Weapons, making it legally binding.
The agreement allows the start of a mission to rid Syria’s regime of its estimated 1,000-ton chemical arsenal by mid-2014, significantly accelerating a destruction timetable that often takes years to complete.
‘‘We expect to have an advance team on the ground [in Syria] next week,’’ spokesman Michael Luhan told reporters at the organization’s headquarters in The Hague, Netherlands immediately after its 41-member executive council approved the plan.
The recent flurry of diplomatic activity followed the Aug. 21 poison gas attack that killed hundreds of civilians in a Damascus suburb, and by President Obama’s threat of US strikes in retaliation.
After Kerry said Assad could avert US military action by turning over ‘‘every single bit of his chemical weapons’’ to international control within a week, Russia quickly agreed. Kerry and Lavrov signed an agreement in Geneva on Sept. 13 to put Syria’s chemical weapons under international control for later destruction, and Assad’s government accepted.