Commentary Center for International Security & Cooperation (Stanford), 03.11.2025 Steven K. Pifer, embajador ® y académico norteamericano (U. de Stanford)
In an October 29 Truth Social post, President Donald Trump said he had ordered the Defense Department to resume testing U.S. nuclear weapons. Four days later, Secretary of Energy Chris Wright clarified that the United States did not intend to conduct nuclear explosive tests.
Indeed, explosive testing of U.S. nuclear warheads is unnecessary. The long-running Stockpile Stewardship Program ensures that warheads in the U.S. nuclear arsenal are safe, secure and effective without the need for explosive testing.
Resumed testing would be unwise. Potential adversaries, while assailing the United States for accelerating a nuclear arms race, would use U.S. testing as the excuse to conduct their own tests, seizing the opportunity to erode the American lead in nuclear weapons knowledge.
Resuming Nuclear Explosive Tests?
Mr. Trump issued his post after Russian tests of the Burevestnik, a nuclear-powered cruise missile, and Poseidon, a nuclear-powered underwater drone, both intended to carry nuclear warheads. Those Russian tests, however, involved delivery systems, not warheads. As Mr. Trump well knows—or should know—the U.S. military regularly tests its nuclear delivery systems. In September, the U.S. Navy conducted four test flights of the Trident D-5 submarine-launched ballistic missile.
On October 31, Secretary of Defense Pete Hegseth told journalists that the Department of Defense would work with the Department of Energy on “resuming testing.” That suggested that Mr. Hegseth thought the president meant tests of nuclear warheads, not delivery systems. Why? The Department of Energy’s National Nuclear Security Administration (NNSA), not the Department of Defense, is the agency that would manage and conduct any nuclear test.
On November 2, Mr. Wright seemed to put the question to rest. He said the administration would not resume nuclear explosive tests but would conduct “non-critical explosions.” That apparently refers to sub-critical experiments, which do not produce a nuclear explosion or a nuclear yield. (In an interview broadcast on November 2, Mr. Trump repeated his position on resuming nuclear testing. However, that interview was taped on October 31; Mr. Wright presumably checked with the White House before making comments that appear to contradict what the president had said earlier.)
Moratorium and Test Ban
Mr. Trump’s October 29 post attributed his order to “other countries [sic] testing programs.” In fact, no country has conducted a nuclear explosive test since North Korea did so in 2017. As for other potential adversaries, China last tested in 1996 and Russia, then part of the Soviet Union, in 1990. The last U.S. test occurred in 1992. With the exception of North Korea, the world’s nuclear weapon states have observed a de facto moratorium on nuclear tests since 1998.
The 1996 Comprehensive Nuclear Test Ban Treaty (CTBT) reinforced the moratorium by banning all nuclear weapons tests or explosions (the 1963 Limited Test Ban Treaty required that any tests be conducted underground). The CTBT has not yet entered into force, in part because the United States and China have not yet ratified it, while Russia rescinded its earlier ratification.
However, treaty signatories have an obligation under international law, before a treaty enters into force, not to take actions that would defeat the treaty’s central purpose. Thus, the United States legally could not test unless it formally withdrew from the CTBT. (The sub-critical experiments to which Mr. Wright seemed to refer do not produce a nuclear yield and thus are not inconsistent with CTBT obligations.)
No Need to Resume U.S. Testing
The United States has no need to resume nuclear explosive testing. Thirty years ago, the United States launched the Stockpile Stewardship Program. Run by the NNSA, the program uses supercomputers and advanced technologies to ensure the safety, security and effectiveness of U.S. nuclear weapons without the need for nuclear explosive testing.
Under the program, the directors of the Lawrence Livermore, Los Alamos and Sandia national laboratories plus the commander of Strategic Command annually certify that U.S. nuclear weapons are reliable. Those certifications have concluded that no technical reason requires nuclear explosive tests.
During visits by the author to the Los Alamos and Sandia national laboratories in 2013, senior lab officials commented that with funding for the Stockpile Stewardship Program, they saw no need for resumed testing. They added that the program had helped them understand things about nuclear explosions that were not well understood solely with testing.
Resumed U.S. Testing Would be Unwise
The Stockpile Stewardship Program built on knowledge and data that the United States gained from conducting 1030 nuclear tests, just over half the world’s total. That compares to 715 for the Soviet Union/Russia, 45 for China and six for North Korea.
The U.S. testing program yielded more knowledge about nuclear weapons and their effects than other countries gained from their tests. Earlier this year, the Trump administration’s NNSA administrator, Brandon Williams, told senators that the United States “collected more data than anyone else” from nuclear tests.
This did not result just from the United States having conducted more tests. When the author served at the American Embassy in Moscow, he accompanied a U.S. team in 1988 to the Soviets’ Semipalatinsk nuclear test site, where among other things the Soviets showed the Americans a vertical shaft for a future underground nuclear test. It was about three feet in diameter. A U.S. team member from the Nevada Test Site (now the Nevada National Security Site) observed that, when the Soviets visited Nevada, they would see that U.S. vertical shafts typically had a diameter of eight to ten feet. The larger diameter allowed for a substantially larger area in the shaft above the nuclear device for more instruments to collect different types of data on an underground nuclear test.
Were the United States to resume testing, it would incur broad international opprobrium for violating the testing moratorium and for undermining the CTBT. It would open the door for other nations to resume testing, while blaming Washington for accelerating a nuclear arms race.
Kremlin spokesman Dmitriy Peskov told the press on October 30 that, if the United States resumed testing, Russia “will respond in kind.” Resumed nuclear explosive testing could be of particular interest to China, which has conducted less than one-twentieth the number of nuclear tests as the United States but has embarked on a major expansion of its nuclear arsenal. Beijing could use an end to the moratorium to conduct tests to help develop lighter and more sophisticated warheads to place atop its strategic ballistic missiles.
Conclusion
The United States in any case could not resume nuclear testing inmediatly. The Biden administration set an objective of conducting an underground nuclear test “within 36 months” of a decision to do so.
Hopefully, wiser heads in the administration will explain to Mr. Trump that the United States does not at this point need to conduct a nuclear explosive test and that doing so would almost certainly trigger a spate of nuclear testing by potential adversary states. That would undermine U.S. security as others gained more knowledge about nuclear weapons effects.
Moreover, Nevada woul oppose a decision to resume nuclear explosive testing there. Las Vegas lies about 65 miles from the Nevada National Security Site, the former location for underground nuclear tests. The population of the Las Vegas metropolitan area today is more than triple the number in 1992, when the last nuclear explosive test took place. Finally, resumed U.S. nuclear testing would hardly help Mr. Trump’s quest for a Nobel Peace Prize.
