The U.N. Security Council approved a resolution Wednesday welcoming stepped up efforts seeking to restart negotiations to end more than 40 years of conflict between Morocco and the pro-independence Polisario Front over the mineral-rich Western Sahara.

The vote on the U.S.-sponsored resolution was 12-0 in favor, with Russia, Ethiopia and Bolivia abstaining. The resolution also extends the mandate of the U.N. mission in the Western Sahara until April 30, 2019.

Morocco annexed the former Spanish colony in 1975 and fought the Polisario Front until the U.N. brokered a cease-fire in 1991 and established a peacekeeping mission to monitor it. Morocco has proposed wide-ranging autonomy for Western Sahara, while the Polisario Front insists the local population, which it estimates at 350,000 to 500,000, has the right to a referendum on the territory's future that was called for in the cease-fire but has never taken place.

Bolivian Ambassador Sasha Llorentty Soliz welcomed an upcoming round table of key parties but complained that the crucial issue of self-determination for the people of Western Sahara "is not reflected sufficiently" in the resolution.

"The Security Council should not neglect the self-determination of Western Sahara," he said.

The resolution welcomes the participation of Morocco, the Polisario Front and neighboring Algeria and Mauritania in a meeting in Geneva on Dec. 5-6 organized by Secretary-General Antonio Guterres' personal envoy, Horst Kohler, the former German president.

The Security Council encouraged the four parties "to work constructively" with Kohler "in the spirit of compromise" to take stock of recent developments, address regional issues, "and discuss the next steps in the political process."

Council members called on Morocco and the Polisario Front to resume negotiations without preconditions, taking into account efforts since 2006 "with a view to achieving a just, lasting and mutually acceptable political solution, which will provide for the self-determination of the people of Western Sahara."

U.S. deputy ambassador Jonathan Cohen told the council that "there can be no more 'business as usual' on Western Sahara."

He stressed that the political process is only beginning and the December round table must start a process of direct negotiations that "proceed swiftly in good faith and without preconditions."

Cohen said that as the process moves forward, the U.S. will carefully evaluate the mandate of the U.N. peacekeeping mission, known as MINURSO.

"Further renewals will not be automatic and will hinge on whether MINURSO is contributing to a political solution," he said.

The Polisario Front's U.N. representative, Sidi Omar, said that "we look forward" to the December round table but he stressed that for it to succeed "we need the Security Council to really keep engaged on this issue."

"It's one thing to bring the parties to the negotiating table and it's an entirely different thing to maintain the momentum for them to move forward towards engaging" on the question of the people of Western Sahara's "fundamental right to self-determination," he said.

Moroccan Ambassador Omar Hilale said, "We are not going to Geneva to help each other."

"We want more than that ... because we are committed to peace," he said. "Why we are committed? Because we want to solve this problem."