By Brahma Chellaney, The HillAP Photo/Evan VucciWas President Trump’s recent directive to resume U.S. nuclear testing — after a hiatus of 33 years — an actual policy decision? Or was it a political stunt to project toughness?His surprise announcement stirred Cold War echoes and revived the old fears of Armageddon and “mutually assured destruction” that once defined nuclear deterrence.The U.S. last conducted a full-scale nuclear explosion in 1992. Russia stopped doing them in 1990, China in 1996. Those moratoria paved the way for the 1996 Comprehensive Test Ban Treaty to prohibit all nuclear testing.Although the treaty never formally entered into force, it has established a powerful international norm. Nations have gained confidence that any nuclear detonation would be quickly detected. Since the treaty opened for signature, no country other than North Korea has carried out a nuclear explosion — and even Pyongyang has maintained a self-declared moratorium since 2018.Yet Trump told reporters aboard Air Force One, while returning from South Korea, that he had decided to restart testing.“We’ve halted it many years ago,” he said. “But with others doing testing, I think it is appropriate that we do also.” On Truth Social, he posted: “Because of other countries’ testing programs, I have instructed the Department of War to start testing our nuclear weapons on an equal basis. That process will begin immediately.”The announcement raised immediate alarms — and eyebrows. For one thing, nuclear testing is not the Pentagon’s responsibility, but that of the Department of Energy’s semi-autonomous National Nuclear Security Administration, which oversees the design, production and stewardship of America’s nuclear arsenal. Trump’s reference to the War Department thus hinted at his unfamiliarity with the institutional framework governing nuclear weapons.His vaguely worded vow to test “on an equal basis” with geopolitical rivals baffled security officials. And his boast that the U.S. has “more nuclear weapons than any other country” was flatly wrong — Russia has several hundred more.Then came more mixed messages. In a “60 Minutes” interview, Trump spoke of denuclearization while simultaneously accusing Russia, China, North Korea and even Pakistan — whose only tests were conducted in 1998 — of “testing nuclear weapons.” Having confirmed his intention to resume tests, he immediately contradicted himself: “I believe we need to do something about denuclearization, and I have indeed discussed it with both [Russian President Vladimir] Putin and President Xi [Jinping of China].”The confusion rattled allies and arms control experts alike. Energy Secretary Chris Wright soon intervened to clarify that any U.S. testing would involve not nuclear explosions but “what we call non-critical explosions” — non-explosive subcritical tests that use nuclear materials but stop short of a self-sustaining nuclear fission chain reaction.In reality, the U.S. has been conducting subcritical tests for decades to ensure the safety and reliability of its weapons stockpile. As Brandon Williams told the Senate during his confirmation hearing as head of the National Nuclear Security Administration, “I would not advise testing, and I think we should rely on the scientific information.”Beyond politics, there are hard technical obstacles to restarting full-scale explosive tests. Facilities at the Nevada National Security Site have degraded, and the specialized know-how to conduct live detonations has largely vanished after decades of reliance on supercomputer modeling and subcritical tests. Launching a live test would take months, if not years — making Trump’s call for “immediate” testing technically impossible.Trump’s announcement appeared to stem partly from anxiety over recent Russian and Chinese developments. Moscow recently claimed to have tested two exotic nuclear-powered and nuclear-capable delivery systems — the Burevestnik cruise missile and the Poseidon underwater drone — designed for nearly unlimited range and stealth. Beijing, meanwhile, is racing ahead with a massive nuclear buildup, more than doubling its warhead inventory since 2020 and expanding its missile silos, submarines and bomber fleets. This surge aligns with China’s goal to achieve global primacy by 2049, the centenary of Communist rule.Against this backdrop, Trump’s abrupt testing directive sent tremors through arms control circles. Even hinting at a return to nuclear testing risks unraveling the global test moratorium. If the U.S. — the principal architect of the test ban treaty — were to abandon restraint, others would likely follow, triggering a destabilizing cascade of nuclear test resumption.Fortunately, Wright’s clarification defused the immediate crisis, reducing Trump’s order to bluster rather than policy. Still, the episode underscored how impulsive presidential words can reverberate globally, unsettling allies and emboldening adversaries.Trump’s brand of nuclear showmanship may play well to a domestic audience seeking toughness, but it highlights the perils of improvisation in nuclear policy. In the nuclear age, restraint is not a sign of weakness but a strategic necessity.History shows that nuclear deterrence rests not only on weapons but on credibility and clarity. When those erode, the risks of miscalculation rise sharply. Trump’s confused directive serves as a reminder that, when it comes to nuclear weapons, even words can be destabilizing — and confusion itself can become a form of danger.Brahma Chellaney is the author of nine books, including the award-winning “Water: Asia’s New Battleground.”