The United States will make an initial payment towards the billions of dollars it owes to the United Nations in a matter of weeks, the US ambassador to the world body told Reuters on Friday, while stressing the need for the UN to continue reforms.

Mike Waltz made the comments in a telephone interview two weeks after UN Secretary-General Antonio Guterres sounded the alarm on UN finances and warned that the 193-country organisation is at risk of “imminent financial collapse” due to unpaid fees, the majority of which are owed by Washington.

“You’ll certainly see an initial tranche of money very shortly,” Waltz said. “It’ll be a significant ... down payment on our annual dues ... I don’t believe that the ultimate figure is decided, but it'll be in a matter of weeks.”

UN officials say more than 95 per cent of what is owed to the regular UN budget is owed by the United States - $2.19 billion by the start of February. The US also owes another $2.4 billion for current and past peace-keeping missions and $43.6 million for UN tribunals.

On December 30, the UN General Assembly approved $3.45 billion for the regular UN budget for 2026, following weeks of negotiations. This covers costs of running UN offices around the world, including the headquarters in New York, staff salaries, meetings and development and human rights work.

The UN funding crisis comes at a time when the United States, under President Donald Trump, has been retreating from multilateralism on numerous fronts. US arrears to the United Nations have grown substantially during this presidency, even though America’s history of falling behind on its UN payments stretches back decades.

UN officials say the US did not pay into the regular budget last year and owes $827 million for that, as well as $767 million for 2026.

Congressional spending bill

On Tuesday, Trump signed into law a spending bill that includes $3.1 billion for US dues to the UN and other international organisations.

Asked if the money he spoke of would go towards last year’s dues or those for 2026, or both, Waltz said: “Just in general, towards the arrears, and also in recognition of some of the reforms that we’ve seen.”

Under Trump, as well as refusing to make mandatory payments to the UN's regular and peacekeeping budgets, the US has slashed voluntary funding to UN agencies with their own budgets, and moved to exit UN organizations including the World Health Organisation.

Waltz said the United States was very supportive of Guterres’ UN80 reform effort and called it an important first step that needed to be continued.

“It doesn’t go far enough, but it’s an important step. I wish the secretary-general had made it in year one or two of his tenure, not year nine,” he said.

“We’re very focused ... on getting back to basics, on peace and security. And ... the president is rightly asking, how can we get the UN back to realising its full potential?

“All of those conversations are currently being had and are in play, and we expect to see more reforms coming,” Waltz said.

‘Tough love’

“This is some tough love. The current model is unsustainable for a lot of countries, and we’re trying to get the UN back, fit for purpose and focused, and stop trying to do everything for everyone.”

Waltz said reducing duplication was a key aim, saying that for example, there were seven UN agencies with climate change as their primary mission.

“Now, regardless of the climate change debate, we don’t need seven,” he said, adding that the US also supported consolidation of logistics and back offices at humanitarian agencies.

“The UN bureaucracy has grown too large, and needs to be much more efficient and effective,” he said.

Guterres launched his UN80 reforms last year, seeking to cut costs and improve efficiency. The approved 2026 regular budget is roughly $200 million higher than he proposed, but about 7 per cent lower than the approved 2025 budget.

He warned last month that the UN could run out of cash by July and cited a “Kafkaesque” requirement for it to credit back hundreds of millions of dollars in unspent dues to states each year even if it never received the money.

Waltz said member states should change this rule.

He said US peacekeeping arrears were in part due to a “statutory disconnect” between what the UN assesses, and what US law allows to be paid and added: “That'll be addressed the next time we negotiate our assessments, which I believe is next year.”