When it comes to nuclear weapons strategy, stability is the goal.
But President Donald Trump’s back-to-back announcements about nuclear testing and nuclear submarines on Oct. 29 during his trip to South Korea could turn the nuclear weapons world upside down.
Although it’s unclear what Trump meant when he ordered that the Pentagon resume nuclear weapons tests “immediately,” nuclear weapons experts and foreign governments alike reacted with shock. The move could end a nearly three-decade period during which none of the world’s major nuclear powers have detonated a nuclear weapon.
Paul Dean, a former acting assistant secretary of State who oversaw arms control, said that Trump’s vague statement could increase the risk of nuclear conflict, “as our adversaries and allies all struggle to understand and interpret what this means.”
Trump’s earlier announcement of a joint nuclear submarine program with South Korea, now overshadowed by his remarks on nuclear testing, could also drastically alter the nuclear weapons balance over time by giving Seoul the ability to quietly prepare a bomb program of its own, experts told USA TODAY.
Ankit Panda, a nuclear strategy expert at the Carnegie Endowment for International Peace, said both moves, though “different in nature,” could significantly destabilize the nuclear landscape.
Will the US detonate a nuclear weapon?
Trump’s Oct. 29 post, which incorrectly claimed the U.S. has a larger nuclear arsenal than Russia, declared that the Pentagon would “start testing our Nuclear Weapons on an equal basis.”
The president did not specify what he meant by “nuclear testing,” and the White House declined to respond on the record to questions from USA TODAY about the announcement. Trump also did not address whether testing could violate the Comprehensive Nuclear Test Ban Treaty, or CTBT, which the U.S. has signed but not ratified.
One interpretation of Trump’s remarks is that he intends to order a nuclear test explosion, whether large or small. Such a test would likely occur underground in Nevada. Alternatively, the president may have meant that he planned to resume unarmed testing of nuclear delivery platforms such as missiles, but the U.S. already routinely tests its nuclear missiles. The Air Force last test-launched an unarmed Minuteman III nuclear missile in May.
Aboard Air Force One after he met with Chinese President Xi Jinping, Trump added that his decision came in response to other countries’ purported testing.
Only North Korea has conducted nuclear test explosions since 1998, according to international testing monitors. But for decades, the U.S. intelligence community has raised concerns that Russia and China have continued to secretly test low-yield nuclear weapons even after both countries, and the U.S., affirmed their halt on nuclear testing in 1996.
U.S. officials have not elaborated on why they believe the tests are happening, and any evidence of them would be highly classified.
But suspicions have swirled for years around Russia’s Novaya Zemlya archipelago, a remote site off the coast of northern Russia, where more than 100 tests were carried out for decades during the Cold War.
The State Department has found that Russia carried out “supercritical nuclear weapons tests” without reporting them since the 1996 moratorium was renewed. “Concerns remain due to these past activities and the uncertainty and lack of transparency relating to Russia’s activities at Novaya Zemlya,” according to the department’s 2025 arms control compliance report.
Increased activity has also been detected in recent years at China’s Lop Nur test site in Xinjiang, an autonomous zone in the country’s northwest. A 2020 State Department report raised concerns that increased activity at the site could mean China was not complying with the testing ban. It did not provide proof.
No ‘channels of communication’ between superpowers
Both Moscow and Beijing expressed concern about Trump’s statement.
Russia recently tested a nuclear-powered cruise missile and a nuclear torpedo, but those tests were unarmed evaluations of the delivery platforms rather than nuclear warheads.
“President Trump mentioned in his statement that other countries are engaged in testing nuclear weapons. Until now, we didn’t know that anyone was testing,” Kremlin spokesman Dmitry Peskov told reporters on Oct. 30. Russian President Vladimir Putin previously said, though, that Russia will resume full-scale nuclear explosive tests if another nation does.
An unarmed Minuteman III intercontinental ballistic missile launches during an operational test from Vandenberg Air Force Base, California at 11:01 p.m. on February 25, 2016.
China’s Foreign Minister Guo Jiakun, addressing reporters in an Oct. 30 press conference, said, “China hopes that the U.S. will earnestly abide by its obligations under the (CTBT) and its commitment to a ‘moratorium on nuclear testing.'”
Dean, the former diplomat who is now at the Nuclear Threat Initiative arms control nonprofit, said the Trump administration needs to clarify its intentions. Because the last nuclear arms control treaty between the U.S. and Russia expires in February, he argued, “This development is more dangerous, and the ambiguity of it is more dangerous when there are not channels of communication for both sides to properly interpret each other’s signals.”
Regardless of Trump’s intent, the U.S. is likely unable to quickly fire a nuclear warhead. Nuclear weapons experts believe that the National Nuclear Security Administration (which is responsible for nuclear tests, not the Pentagon) is not prepared to detonate a nuclear weapon “immediately.” The agency declined to provide USA TODAY an on-the-record comment.
Nuclear submarines for Seoul
Trump’s nuclear testing announcement was not his only nuclear-related move that made waves during his Asia trip.
He granted a request from South Korean President Lee Jae Myung to assist the U.S. ally in building nuclear-powered military submarines.
While such ships wouldn’t be armed with nuclear weapons, “most or all” nuclear-powered subs “are fueled by high-enriched uranium” that can approach weapons-grade levels of purity, according to the World Nuclear Association.
Trump, when announcing the submarine deal, did not specify their fuel arrangement, which will greatly influence whether South Korea’s submarine program could also support a bomb-building project.
But Lee, during his meeting with Trump, asked that the U.S. provide South Korea the ability to supply fuel to the proposed submarines, which would likely require the establishment of domestic uranium enrichment capabilities. U.S. diplomats have traditionally opposed allowing the Koreans to enrich uranium due to the nuclear weapons risk.
A majority of South Koreans support building nuclear weapons, and the issue is a subject of domestic political debate.
South Korean President Lee Jae Myung gestures as he meets with President Donald Trump on the sidelines of the Asia-Pacific Economic Cooperation (APEC) leaders’ summit in Gyeongju, South Korea, Oct. 29, 2025.
Victor Cha, a Georgetown government professor and top Korea expert at the Center for Strategic and International Studies think tank, told USA TODAY that the move “will give (South) Korea a latent nuke capability” if it establishes Seoul’s ability to enrich uranium for the first time.
Nuclear latency, according to weapons experts, is when a country does not have a nuclear weapons development program but maintains the knowledge, technology and infrastructure to rapidly build the bomb if needed.
Panda, the Carnegie Endowment expert, said that South Korea likely sees value in nuclear latency due to an increasingly uncertain relationship with the United States.
“This is a big development in the alliance and a big change in U.S. policy,” Cha said, adding that he believes the project is “good for (South) Korea and good for the alliance.”
The submarine agreement, by boosting nuclear latency and enhancing Seoul’s naval power against threats from China and North Korea, could strengthen the alliance.
Not all experts believe that it would be good for South Korea to build nuclear weapons, though, because the move could provoke North Korea or harm the global economy by bringing international sanctions down on Seoul and its high-tech industries for violating treaties against developing nukes.
Contributing: Reuters
Davis Winkie’s role covering nuclear threats and national security at USA TODAY is supported by a partnership with Outrider Foundation and Journalism Funding Partners. Funders do not provide editorial input.
This article originally appeared on USA TODAY: Trump turned the nuclear weapons world upside down in three hours
