‘Bad news for South Korea’ as US-Russia nuclear pact expires, sparking fears of arms race

The end of the New Strategic Arms Reduction Treaty will be a blow to efforts to curb North Korea’s nuclear build-up, analysts say

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A test-fire of a large-calibre multiple-rocket launcher system at an unknown location in North Korea on January 27. Photo: EPA/KCNA

Published: 10:00am, 6 Feb 2026Updated: 5:30pm, 6 Feb 2026

Fears over the weakening of global momentum to rein in North Korea’s nuclear ambitions have mounted with the expiration of the New Strategic Arms Reduction Treaty (New Start) between the United States and Russia, with observers warning that an emboldened Pyongyang could also spark a domino effect regionally.

For 15 years, the treaty functioned as a stabilising force between the world’s two largest nuclear powers, setting limits on deployed strategic nuclear warheads and delivery systems while institutionalising transparency through inspections and regular communication.

Its lapse, analysts warn, risks normalising nuclear expansion, especially for North Korea, at a time when denuclearisation norms are already under strain.

Shin Beom-cheol, a senior research fellow at the Sejong Institute, said international pressure on Pyongyang to denuclearise could weaken following the treaty’s expiration, giving the secretive regime room to justify further arms expansion.

“This is bad news for South Korea and the region, as it would deal a blow to international efforts to curb North Korea’s nuclear build-up while giving the North an excuse to step up its nuclear development,” Shin told This Week in Asia.

“South Korea and Japan would come under increasing pressure to bolster their defence capabilities, as they possess no nuclear weapons and rely entirely on the US nuclear umbrella, while being surrounded by North Korea, China and Russia.”

South Korea must strengthen its security posture, including accelerating plans for nuclear-powered submarines, to prepare even for “worst-case scenarios”, at a time when the US was reducing its level of regional engagement, Shin said.

‘Bad news for South Korea’ as US-Russia nuclear pact expires, sparking fears of arms race

.css-1c6uqr6{color:inherit;font-weight:inherit;font-size:inherit;font-family:inherit;line-height:inherit;overflow-wrap:break-word;}The end of the New Strategic Arms Reduction Treaty will be a blow to efforts to curb North Korea’s nuclear build-up, analysts say

The end of the New Strategic Arms Reduction Treaty will be a blow to efforts to curb North Korea’s nuclear build-up, analysts say