The UN Security Council has unanimously adopted Resolution 2254, endorsing progress towards peace in Syria.
The resolution allows the UN to facilitate talks between the government and opposition members in January, and to begin moving towards nationwide ceasefire.
The council has also reconfirmed its previous "Vienna Statements" endorsement, which supported the implementation of the 2012 Geneva Communiqué as the basis for a Syrian-led political transition.
The UN will also support Syria in transforming political processes to establish credible, inclusive, and non-sectarian governance within six months, as well as schedule the drafting of a new constitution.
The council expressed support for free and fair elections in the country within 18 months, based on the new constitution.
UN Secretary-General Ban Ki-moon said: "This marks a very important step on which we must build."
The Secretary urged the support group to pressure Syrian parties to end the indiscriminate use of weapons against civilians, halt attacks on medical and educational facilities, lift restrictions on medical supplies from humanitarian convoys, and release all detainees.
US Secretary of State John Kerry said that the adopted resolution sent a clear message to stop the killing in Syria.