China’s Covert Test May Signal a Shift in Beijing’s Nuclear Posture 

China is actively modernizing and expanding its nuclear arsenal to incorporate next-generation capabilities.

Citing sources familiar with U.S. intelligence assessments, a February 21 CNN report noted the conclusion reached by American agencies that a covert low-yield nuclear test conducted by China in June 2020 was aimed at developing next-generation nuclear weapons. These may include low-yield tactical nuclear weapons, which Beijing has not previously produced, and new delivery systems, such as missiles capable of carrying multiple miniaturized nuclear warheads on a single platform.

These developments, amid China’s large-scale nuclear build-up, suggest Beijing may be moving beyond its longstanding policy of minimal deterrence and no-first-use toward a more flexible and potentially aggressive posture.

U.S. Intelligence Links Chinese Test to Next-Generation Nuclear Weapons

According to U.S. intelligence, the covert June 2020 test advanced China’s tactical nuclear weapons program as well as technology akin to multiple independent reentry vehicle (MIRV) systems. While the Comprehensive Test Ban Treaty Organization — the agency that records data on potential nuclear tests — cannot reliably detect explosions below roughly 500 tons in yield, Christopher Yeaw, assistant secretary of state for arms control and nonproliferation, stated that the United States detected seismic activity of magnitude 2.75 from China’s Lop Nur nuclear test site in June 2020, consistent with a small-scale explosive test.

Unlike the strategic nuclear warheads carried by the intercontinental ballistic missiles that dominate China’s current arsenal, tactical nuclear weapons — typically defined as weapons with yields under one kiloton — are designed for battlefield use and could have caused the detected seismic activity. Over the past five years, China has also worked to develop and deploy MIRV-capable systems, which enhance the flexibility of its current silo-based and road-mobile forces and could eventually enable Beijing to strike multiple targets with nuclear warheads using a single missile.

Beijing’s Rapid Build-Up Introduces New Uncertainty Over Nuclear Doctrine

China’s efforts are injecting growing uncertainty into assessments of Beijing’s nuclear use doctrine, which Chinese officials insist remains unchanged despite the build-up. Officially, China remains wedded to its policy of “no first use” of nuclear weapons, declaring that its arsenal exists solely to deter a nuclear first strike and ensure retaliation.

However, the U.S. Department of Defense’s 2025 annual report on Chinese military developments noted that Beijing is likely aiming to leverage its growing arsenal to deter and respond to conventional conflicts as well. This shift would align with China’s efforts to field tactical nuclear weapons unsuitable for deterring a surprise strategic nuclear attack, but are potentially useful for countering U.S. or allied conventional forces in the Indo-Pacific.

Beijing has also become more confident about showcasing its nuclear forces while leveraging them for perceived political gain. Despite previously displaying each leg of its nuclear triad (land-, sea-, and air-based systems) separately, Beijing publicly unveiled them together for the first time during its September 2025 Victory Day military parade. This also featured other new, advanced weapons platforms. Chinese state-affiliated media have similarly escalated nuclear rhetoric, including coercive threats against Japan over its support for Taiwan.

The United States Should Focus on Curbing a Trilateral Arms Race

China’s push to develop MIRV systems and a tactical nuclear weapons program — a class of warheads not constrained by the now expired U.S.-Russia nuclear treaty, New START — underscores the urgent need for Washington to conduct a comprehensive nuclear posture review. While the administration reportedly evaluated its nuclear strategy in a classified portion of the National Defense Strategy, released in January 2026, a more extensive review in the post-New START environment would help the United States evaluate its force requirements and respond to ongoing nuclear modernization and expansion by both Moscow and Beijing.

The Trump administration should undertake such a review while pursuing efforts to engage Russia and China in talks on a potential follow-on arms control agreement. The goal of a future accord would be to curb a possible trilateral arms race and restore elements of strategic stability in an increasingly multipolar nuclear environment.

Jack Burnham is a senior research analyst in the China Program at the Foundation for Defense of Democracies (FDD). Andrea Stricker is a research fellow and deputy director of FDD’s Nonproliferation Program. Follow them on X @JackBurnham802 and @StrickerNonpro. For more analysis from Jack, Andrea, and FDD, please subscribe HERE. Follow FDD on X @FDD. FDD is a Washington, DC-based, nonpartisan research institute focusing on national security and foreign policy.