The United Nations will reduce its peacekeeping forces and operations, forcing 13,000 to 14,000 personnel to return home in the coming months due to U.S. funding cuts, a senior U.N. official said.

The reductions, representing roughly 25% of the deployed peacekeepers, will affect missions in countries including Congo, South Sudan, Lebanon, Cyprus, and Kosovo, and slash the force’s budget by about 15% this year.

U.S. officials, including Ambassador Mike Waltz, argue the cuts aim to streamline the U.N. and focus on core peacekeeping functions, part of a broader “America First” review that has already reduced U.S. contributions to agencies like UNESCO and WHO.

U.N. Secretary-General António Guterres warned that peacekeeping remains a cost-effective tool for global security, representing only 0.5% of worldwide military spending, the Associated Press has reported.

The U.S. will contribute $680 million to nine key missions, down from $1 billion last year, while China has committed to paying its full share of the peacekeeping budget.