Letter Text (PDF)

Boston (November 25, 2025) – Senator Edward J. Markey (D-Mass.), a co-chair of the bicameral Nuclear Weapons and Arms Control Working Group, today wrote to President Trump, urging him to refrain from restarting the United States’ nuclear testing program. To do so, he writes, would be a “mistake of radioactive proportions.”

President Trump has been undeterred by the facts surrounding nuclear testing in recent weeks. He has claimed he wants to conduct nuclear tests because other nations are doing so, but they are not. He has also appeared to double down on this dangerous and misguided path, having said that Russia and China are conducting nuclear tests in secret.

In the letter, Senator Markey writes, “You have suggested that Russia and China are conducting small nuclear tests that are hard to detect, sometimes referred to as ‘hydronuclear’ tests, in violation of U.S. policy and the Comprehensive Test Ban Treaty. Reports of such tests from 2019 raise concerns, but they are unconfirmed. Even if true, they would not justify renewed U.S. nuclear testing. Make no mistake—small nuclear tests are still nuclear tests.”

Senator Markey continues, “With no need to resume nuclear testing, it appears that the root cause of this entire kerfuffle is your confusion about what a nuclear test is and is not. Russia recently tested two new missiles—called Poseidon and Skyfall—that are designed to evade U.S. missile defenses. But there were no nuclear warheads on these missiles. You apparently mixed up the testing of missiles that deliver nuclear weapons to their targets and the testing of the nuclear bombs that those missiles carry. Russia did not test nuclear bombs.”

Senator Markey concludes, “Accordingly, I am compelled to ask whether you are proposing to resume U.S. nuclear testing with the intention of initiating a new nuclear arms race, or whether your statements reflect a misunderstanding of the difference between missile tests and nuclear explosive tests. As horrific as it sounds, it seems that you may be on the verge of undermining U.S. and global security just so you don’t have to admit that you were wrong.”

Senator Markey requests a response to questions including:

• What evidence do you have to support your claim that Russia and China are conducting secret nuclear tests?

• What would be the purpose of new U.S. nuclear tests? What, if any, technical information would be gained?

• Given that Russia has announced that it will resume nuclear testing if the United States does, how would the United States respond to new Russian nuclear tests?

• If China resumes nuclear tests in response to U.S. tests, how useful, in terms of gaining confidence in its current warhead designs or in new designs, would additional tests be to Beijing?

• What would be the impact of renewed U.S. nuclear testing on the testing programs of North Korea, India, and Pakistan?

As a founder of the national Nuclear Freeze movement, Senator Markey has worked to end the proliferation of nuclear weapons since the beginning of his career.

• In 1986, then-Representative Markey co-authored an amendment that passed in the House of Representatives to establish a moratorium on all nuclear tests in excess of one kiloton, provided the Soviet Union observed similar limits. This provision laid a vital foundation for the subsequent moratorium on all U.S. nuclear tests and for the negotiation of the CTBT.

• In May 2020, in response to fears of a return to nuclear testing, Senator Markey sent a letter to President Donald Trump arguing there was no justification to restart nuclear testing.

Senator Markey has long been a champion pushing for deep and verifiable reductions in nuclear arsenals.

• In November, Senator Markey and Representative Joaquin Castro (TX-20) wrote to Secretary of State Marco Rubio, urging the Trump administration to include the strongest possible “gold standard” nonproliferation measures in any nuclear cooperation agreement with the Kingdom of Saudi Arabia to foreclose any pathway to a nuclear weapon.

• In October, Senator Markey published an op-ed detailing the accuracy with which director Kathryn Bigelow’s new film, “A House of Dynamite,” presents the dangers of nuclear war and the risks of depending on unreliable missile defenses at the expense of a nuclear security policy centered on arms reduction and non-proliferation. He also spoke with her about the film, including takeaways for the American public and policymakers.

• Also in October, Senator Markey introduced the No Nuclear Testing Act, which would use Congress’s power of the purse to deny the Trump administration from restarting nuclear testing.

• In July, Senator Markey introduced the Senate companion to H.Res.317, urging the United States to lead the world in halting the nuclear arms race.

• In February, Senator Markey introduced a resolution to recommit the United States to arms control, one year ahead of the expiration of New START.

• In January, Senator Markey reintroduced a bill with Rep. Ted Lieu (D-CA) to ensure that no president can start a nuclear war without congressional approval.

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