Trump Weighs Expanding Nuclear Arsenal and Resuming Underground Tests After New START Expires

The expiration of the New Strategic Arms Reduction Treaty (New START) on February 5 has left the United States and Russia without any binding limits on their nuclear arsenals for the first time in more than half a century — and the Trump administration is already exploring what that freedom means in practice.

According to reporting by The New York Times, senior administration officials are actively weighing two historic moves: expanding the number of nuclear warheads deployed on missiles, bombers, and submarines, and conducting underground nuclear weapons tests for the first time since 1992.

Either step would reverse nearly 40 years of U.S. nuclear restraint. No president since Ronald Reagan has increased the deployed arsenal, and no president since George H.W. Bush has authorized a nuclear test explosion.

The End of New START

New START, signed in 2010, capped both the U.S. and Russia at 1,550 deployed strategic warheads and 700 deployed delivery systems. Russia suspended participation in 2023, and neither side pursued an extension before the treaty's February 2026 expiration.

While Axios reported that both nations have informally agreed to observe the treaty's limits even after expiration, the Trump administration has signaled it views the post-treaty landscape as an opportunity.

Underground Testing: Breaking a 34-Year Moratorium

President Trump first raised the prospect of resumed nuclear testing in October 2025, writing on social media that he had "instructed the Department of War to start testing our Nuclear Weapons" in response to what he characterized as secret Russian and Chinese testing programs.

According to the BBC, no country except North Korea has conducted a nuclear test explosion this century. The Arms Control Association notes that any U.S. test would effectively end the global testing moratorium that has held since the 1990s.

Global Implications

Arms control experts warn that expanding the U.S. arsenal could trigger a three-way arms race involving Russia and China. Beijing has been rapidly modernizing its nuclear forces, with the Pentagon estimating China could have over 1,000 warheads by 2030 — though that would still be far fewer than the roughly 5,500 held by both the U.S. and Russia.

The decision to test would also have diplomatic consequences. The Comprehensive Nuclear-Test-Ban Treaty (CTBT), which the U.S. signed but never ratified, has been a cornerstone of international nonproliferation efforts since 1996.

"We are entering genuinely uncharted territory," said Daryl Kimball, executive director of the Arms Control Association. "The guardrails that prevented nuclear competition for decades are being dismantled one by one."

What Happens Next

No final decisions have been made, officials told The New York Times. The administration is reportedly conducting internal reviews on both the feasibility of expanding the deployed arsenal and the logistics of resuming underground tests at the Nevada National Security Site.

Congressional support for expanded nuclear capabilities appears strong among Republican lawmakers, though some Democrats have warned the moves could be destabilizing.

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