The world's nine nuclear-armed states jointly increased their spending on their arsenals by nearly $17 billion last year, according to a new report from the International Campaign to Abolish Nuclear Weapons.

At a time of growing geopolitical tensions, "a new nuclear arms race is upon us, one which the perpetrators themselves are preparing to last for decades", the ICAN report warned.

Susi Snyder, ICAN's director of programmes and co-author of that report, said the scale-up, coupled with fears that artificial intelligence could increase the risk of nuclear weapons use, was deeply alarming.

"To be perfectly honest, I'm terrified," she told AFP.

The study showed that all of the nuclear-armed states -- Britain, China, France, India, Israel, North Korea, Pakistan, Russia, and the United States - increased their spending last year.

Washington spent more than all the other countries combined, dishing out $69.2 billion on nuclear weapons in 2025 -- an increase of $12.4 billion from a year earlier, the report showed.

It was followed by China, which was estimated to have spent $13.5 billion last year, then Britain at $12.6 billion and Russia at $9.5 billion, the report showed.

And over the past five years, ICAN, which won the 2017 Nobel Peace Prize, found that the nine countries had spent over $470 billion on their arsenals.

Those investments are only expected to grow going forward.

Examining longer-term spending growth projections, ICAN highlighted figures from Britain, France and the United States showing plans to spend billions to develop and maintain such weapons systems well into the next century.

Other countries too were introducing new weapons systems with long lifespans, it said.

The report pointed out that new planned US Sentinel intercontinental ballistic missiles were expected to remain operational past 2100, while swelling US plutonium pit production indicated that the country's warheads would last through 2120.

That will mean significant investments, with US nuclear arms spending over just the decade between 2025 and 2034 projected at close to $1 trillion, the report said.

The researchers said the huge sums being spent were particularly jarring at a time when the global humanitarian system was reeling from dramatic funding cuts.

"What these countries spent in 2025 could have paid 32 years of the UN operating budget," Snyder pointed out, adding that a single day of nuclear weapons spending last year could have provided food security to more than two million people.

Instead of providing aid or guaranteeing essential services like healthcare for their populations, the nuclear-armed states were investing in "an arsenal that they themselves know they cannot use without committing a war crime", Snyder said.

"There seems to be a total disconnect from reality."