( BSS/AFP) - The UN Security Council on Thursday passed a resolution extending the United Nations peacekeeping mission in South Sudan (UNMISS) by one year but reducing its size, despite pushback from several member states.

The resolution, adopted with 13 votes in favor and abstentions from Russia and China, prolongs the mission until April 30, 2027.

The mission, which began in 2011 when South Sudan first gained independence, will have a new cap of authorized peacekeepers with a maximum of 12,500 soldiers -- down from the previous limit of 17,000 soldiers -- as well as some 2,100 police officers.

The resolution also asks the Office of the Secretary-General to conduct a "capability study" of the mission within the next 120 days to assess "the adequacy of the Mission`s current force levels."

The reduction in peacekeeping troops drew ire from China, Russia and Pakistan, as well as the three African nations currently on the council: Somalia, Liberia and the Democratic Republic of Congo.

However, the new cap will not reduce the number of peacekeepers currently deployed in South Sudan, as the mission has already had to downsize due to budget cuts.

According to UN figures, UNMISS had about 9,000 soldiers on the ground at the end of March, a sharp decrease from nearly 14,000 deployed a year ago.

"The contingency drawdown has already affected the mission`s functions in protecting civilians and assisting in humanitarian aid," Chinese Ambassador Sun Lei said, adding that the UNMISS should instead be "optimized and strengthened" given recent developments in the country.

Russian Deputy Ambassador Anna Evstigneeva for her part said the peacekeeping mission should have a "sufficient level of resources" to "be ready for any scenarios."

The resolution passed Thursday was the result of a painstaking compromise, diplomatic sources told AFP, as the United States, which drafted the text, wanted initially to reduce the maximum number of troops to 7,000.

As a result, US Ambassador Mike Waltz expressed disappointment, though he voted for the resolution, noting that it was still "taking a serious step to streamline UNMISS."

"We spent considerable time debating mandate language and operational adjustments...when the core problem is staring us right in the face. The core problem is a host government that actively undermines its commitments to peace and the mission it agreed to accept," he added.

Since gaining independence in 2011, South Sudan has been the site of several deadly conflicts.

Recent weeks have seen a resurgence in fighting between government forces loyal to President Salva Kiir and opposition militias supporting suspended vice president Riek Machar, who was placed under house arrest last year.