US defence bill opens path to restart underground nuclear testing

The Pentagon would be authorised to resume underground nuclear weapons testing under a provision in the fiscal 2026 National Defence Authorisation Act, which is nearing a final vote in the US Senate.

According to US media, the 3,086-page bill includes a section on Energy Department national nuclear security activities that would effectively end the United States’ self-imposed moratorium on underground nuclear tests, in place since 1996. 

The provision states that the ban remains in effect unless a foreign state conducts a nuclear test, at which point the prohibition on US underground testing would be lifted. As a result, North Korea’s six underground nuclear tests between 2006 and 2017 would already meet that condition, allowing the Pentagon and the Energy Department’s National Nuclear Security Administration to resume such tests.

While permitting underground testing, the legislation maintains the ban on atmospheric nuclear tests. The bill, which passed the House this week and is expected to clear the Senate shortly, authorises $890.6 billion in spending for fiscal 2026, including $855.7 billion for Pentagon programs, $34.3 billion for national security programs at the Energy Department, and $512.4 million for defence-related activities.

The policy shift follows statements by President Trump last month that the United States will resume nuclear testing in response to testing by Russia, China, and North Korea. In an interview with CBS’s 60 Minutes, Trump said the US should not be the only country refraining from tests and confirmed that underground detonations would resume. He reiterated the position in an October 29 post on Truth Social, citing US nuclear superiority and directing what he called the Department of War to begin testing “on an equal basis.”

Despite backing renewed testing, Trump said he supports nuclear arms reduction talks and has raised the issue with Russian President Vladimir Putin and Chinese President Xi Jinping. He argued that testing is necessary to ensure the reliability, or “assurance,” of US nuclear weapons, many of which are decades old and have so far been maintained without testing under the Stockpile Stewardship Program.

Following Trump’s remarks, CIA Director John Ratcliffe said Russia and China have conducted nuclear tests, citing prior congressional testimony that Moscow violated a zero-testing moratorium and a 2020 report suggesting a possible Chinese test. Russia and China both responded to the US position.

On December 5, Putin said he had instructed officials to prepare proposals on steps toward nuclear weapons testing. China’s Foreign Ministry denied conducting secret tests, reaffirmed its testing moratorium and “no first use” policy, and urged the US to uphold its own moratorium.

US officials say North Korea has not conducted an underground nuclear test since September 2017, but intelligence activity at the Punggye-ri test site indicates Pyongyang could resume testing in the near future.

By Tamilla Hasanova