The U.N. chief is warning that the world body faces “imminent financial collapse” unless its financial rules are overhauled or all 193 member nations pay their dues — a message likely directed at the United States and the billions it owes.

Secretary-General Antonio Guterres said in a letter to all U.N. member nations obtained Friday by The Associated Press that cash for its regular operating budget could run out by July, which could dramatically affect its operations.

“Either all member states honor their obligations to pay in full and on time — or member states must fundamentally overhaul our financial rules to prevent an imminent financial collapse,” he said.

While Guterres did not name any country in the letter, which was reported earlier by Reuters, the financial crisis comes as the U.S., traditionally the largest donor, has not paid its mandatory dues to the U.N.

The U.S. now owes $2.196 billion to the U.N.’s regular budget, plus it will owe $767 million for this year, according to a U.N. official, who was not authorized to comment publicly and spoke on condition of anonymity. The U.S. also owes $1.8 billion for the separate budget for the U.N.’s far-flung peacekeeping operations, and that also will rise.

The country second on the list for not paying dues is Venezuela, which owes $38 million, the official said. The country, whose economy was struggling before the U.S. military raid this month that deposed then-President Nicolas Maduro, has already lost its right to vote in the General Assembly for being two years in arrears.

Guterres said the U.N. ended 2025 with a record $1.568 billion in outstanding dues, more than double the amount outstanding at the end of 2024. The U.N. official said the Trump administration did not pay any dues last year.

Because so much is owed, the U.N.’s liquidity reserves nearly have been exhausted, Guterres said, and unless payments drastically improve, the U.N. will not be able to fulfill the $3.45 billion regular budget for 2026 approved unanimously in December by the assembly’s 193 members.

The secretary-general stressed another major problem that he has raised repeatedly: Under U.N. financial rules, the organization is required to pay back unspent money from the regular budget to member states — even if it hasn’t received that money in payments. He urged U.N. member nations to change the requirement immediately.

“I cannot overstate the urgency of the situation we now face,” he said. “We cannot execute budgets with uncollected funds, nor return funds we never received.”

The U.S. mission to the U.N. didn't immediately respond to a message seeking comment.