China’s nuclear arsenal has grown faster than that of any other country, reaching an estimated 600 warheads by early 2025, adding momentum to the global arms race and raising strategic concerns, an independent international institute said Monday.

The country's nuclear stockpile has been expanding by roughly 100 warheads per year since 2023, the Stockholm International Peace Research Institute (SIPRI) said in its SIPRI Yearbook 2025, warning that a new and dangerous nuclear arms race is taking shape amid a widespread weakening of arms control frameworks.

According to the report, by January this year, China had built or nearly completed around 350 new intercontinental ballistic missile (ICBM) silos and could have at least as many ICBMs as either Russia or the US by the turn of the decade.

The report said, however, that even if China reaches 1,500 warheads by 2035, this would still represent only about a third of each of the current Russian and US stockpiles.

The report also revealed that nearly all nine nuclear-armed states -- the US, Russia, the UK, France, China, India, Pakistan, North Korea and Israel -- continued to modernise and expand their nuclear capabilities in 2024.

The overall global nuclear inventory declined slightly to 12,241, the report said, while nevertheless expressing concern that a "dangerous new nuclear arms race is emerging."

Russia maintains the world's largest arsenal, at 5,459 warheads, while the US has 5,177 warheads. The two nations account for about 90% of the world's total, the report said.

Israel has 90 warheads, although the country has not confirmed its nuclear arsenal.

It is believed to be modernising its capabilities and conducting a test of a missile propulsion system in 2024 and also appears to be upgrading its plutonium production reactor site at Dimona.

North Korea was estimated to possess around 50 nuclear warheads as of January, the same as last year. It possesses enough fissile material to produce up to 40 more nuclear warheads.

Longtime rivals Pakistan and India are believed to have expanded their nuclear programs in 2024, according to the report.

India is believed to have once again slightly expanded its nuclear arsenal in 2024 and continued to develop new types of nuclear delivery systems. It possesses 180 nuclear warheads compared to 172 last year.

Pakistan also continued to develop new delivery systems and accumulate fissile material in 2024, suggesting that its nuclear arsenal might expand over the coming decade.

It is believed to possess 170 nuclear warheads, the same as in 2024.

A brief armed conflict between the two nations in May highlighted the risks of escalation.