United Nations Secretary-General Antonio Guterres said on Thursday that the billions of dollars the United States owes to the world body is “non-negotiable,” after reports that Washington had placed conditions on releasing the funds.

The development newswire Devex reported this week that two diplomatic notes circulated by the U.S. called for nine “quick-hit” reforms as a condition for releasing more funds, including further cost-cutting, and moves to counter China’s influence at the United Nations.

“The money we are talking about is referred to as assessed contributions,” Guterres told reporters when asked about the reports. “Assessed contributions are an obligation of member states. They are non-negotiable.”

Guterres, who has been leading reform efforts under pressure from member states, especially the United States, said the U.N. would do its best “to make sure that we make this organization as effective and as cost-effective and as able to deliver for the people we care for.”

“But these are two separate things,” he added.

According to Devex, the U.S.-demanded cost-cutting included overhauling the U.N. pension system, ending long-distance business-class travel for some senior and all mid-level professionals, additional cuts to senior U.N. ranks and a 10% reduction in long-running and ineffective peacekeeping missions.