The United States has accused China of carrying out a secret nuclear explosive test in June 2020, just days after the deadly Galwan Valley clashes.
The United States has accused China of conducting a covert nuclear explosive test on June 22, 2020 — just a week after the deadly Galwan Valley clash in which 20 Indian soldiers were killed. The allegation comes amid renewed calls for a global arms control framework following the expiry of the New START treaty, which limits the number of deployed strategic nuclear warheads.
US Under Secretary of State for Arms Control and International Security Thomas G. DiNanno said China used techniques to evade international monitoring while carrying out yield-producing nuclear tests. He added that Beijing employed “decoupling” to reduce the effectiveness of seismic monitoring and conceal its activities.
“Exact zero Chinese nuclear weapons were covered by New START,” DiNanno noted, highlighting China’s unchecked nuclear expansion.
US calls for a new nuclear architecture
“This confluence of factors – serial Russian violations, growth of worldwide stockpiles, and flaws in New START’s design and implementation – gives the United States a clear imperative to call for a new architecture that addresses the threats of today, not those of a bygone era,” DiNanno wrote on X.
He said the US has long pursued arms control that is “verifiable, enforceable, and contributes to the security” of the United States and its allies. “What we are proposing is not talks for the sake of talks — we are seeking meaningful progress based on concrete actions,” he added.
Earlier, on Substack, US Secretary of State Marco Rubio warned that Russia and China “should not expect” the United States to remain idle “while they shirk their obligations and expand their nuclear forces.”
“We will maintain a robust, credible, and modernised nuclear deterrent,” Rubio added.
The Galwan Valley clash and military build-up
The alleged nuclear test came a week after Indian and Chinese troops clashed in eastern Ladakh on June 15, 2020. Twenty Indian soldiers were killed, while intelligence reports estimated Chinese casualties at more than 30 — though Beijing officially acknowledged only four deaths. The episode underscores China’s aggressive posture along the Line of Actual Control.
New START treaty expires
DiNanno’s remarks coincided with the formal expiry of the New START treaty, the last binding nuclear arms control pact between the United States and Russia, leaving the world’s two largest nuclear powers without limits on their strategic arsenals for the first time in over five decades.
He warned that the treaty no longer reflects today’s nuclear landscape, with one power expanding its arsenal at a pace unseen in over 50 years and another maintaining a vast stockpile largely unconstrained.
US pushes for China’s inclusion
US President Donald Trump has stressed that any future treaty must include China. “I actually feel strongly that if we’re going to do it, I think China should be a member of the extension. China should be a part of the agreement,” Trump told the New York Times.
China, however, has rejected participation. Beijing has repeatedly emphasised that its nuclear arsenal — around 600 warheads — is far smaller than those of the US and Russia, and said it will not join disarmament talks at this stage.
Chinese foreign ministry spokesperson Lin Jian said, “China’s nuclear forces are not at all on the same scale as those of the US and Russia, and thus China will not participate in nuclear disarmament negotiations at the current stage.” He added that China regrets New START’s expiration but urged the US to resume talks with Russia.
What is New START?
Signed in 2010 by US President Barack Obama and Russian President Dmitry Medvedev, the New START treaty limited each side to 1,550 deployed warheads on up to 700 missiles and bombers. Originally set to expire in 2021, it was extended for five years.
In February 2023, Russian President Vladimir Putin suspended Moscow’s participation, citing concerns over US inspections amid NATO opposition related to the Ukraine war, but pledged to respect nuclear limits. He later warned that the treaty’s expiration could destabilise global security and fuel nuclear proliferation, offering to uphold the limits for a year while negotiations continue.
New START was one of the last remaining US-Russia nuclear arms agreements, part of a series of pacts dating back to SALT I in 1972.
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