The U.N. Security Council voted Thursday to authorize delivery of humanitarian aid across borders and conflict lines in Syria for another year, expressing "outrage" at the continuing violence in the country and "grave distress" at the devastating humanitarian situation.

The resolution, sponsored by Kuwait and Sweden, was adopted by a vote of 13-0, with Syria's main council ally Russia abstaining along with China.

U.N. humanitarian chief Mark Lowcock thanked the council for approving the resolution, saying that "cross-border aid provides a critical lifeline for millions of Syrians who cannot be supported through other means."

"You have done your part; we will now do ours to sustain aid in a way that is as effective and accountable as possible," he said.

Lowcock said the situation is especially "very challenging" in northwestern Syria, where some 3 million people remain dependent on cross-border aid.

While a pause in airstrikes has been positive, he said, shelling and fighting continues in and around the demilitarized zone and recent hostilities forced nearly 15,000 people to flee their homes to neighboring villages.

Lowcock also warned that Idlib, the last major rebel stronghold in Syria, "remains on the edge of a humanitarian disaster."

He said a further escalation of violence "would quickly overwhelm the ability of humanitarian agencies to respond." He urged the warring parties to end the violence and head of the "humanitarian catastrophe" that Secretary-General Antonio Guterres has warned about.

Syrian Ambassador Bashar Ja'afari criticized the resolution for deliberately avoiding Syrian sovereignty.

Russia's ambassador, Vassily Nebenzia, said Moscow abstained because "the new realities in Syria" require that the program for cross-border deliveries be fine-tuned "with the ultimate goal here being to gradually but inevitably wrap it up," but this was not included in the resolution.

"We decided not to block the decision because of humanitarian considerations and also taking into account appeals from our partners in the region," Nebenzia said.

The resolution expresses "outrage at the unacceptable level of violence and the killing of hundreds of thousands of people, including tens of thousands of child casualties, as a result of the Syrian conflict," which began in 2013.

The Security Council reiterated "its grave distress at the continued devastating humanitarian situation in Syria and at the fact that urgent humanitarian assistance, including medical assistance, is required by more than 13 million people," including 6.2 million who have fled their homes and more than 1 million still living in hard-to-reach areas.

The resolution renewed cross-border deliveries until Jan. 10, 2020, demanded unimpeded access for humanitarian convoys from the U.N. and its partners, and stressed that "the situation will continue to deteriorate further in the absence of a political solution to the Syrian conflict."

The council again warned that "it will take further measures" — U.N. language for sanctions — against those violating the resolution.