RESTRAIN Act Prohibits All U.S. Nuclear Explosive Testing Starting FY2026, While Allowing Subcritical Tests

The aptly named Renewing Efforts to Suspend Testing and Reinforce Arms-control Initiatives Now Act, or the RESTRAIN Act, is a direct, no-nonsense piece of legislation that puts a definitive end to U.S. nuclear explosive testing. Starting in fiscal year 2026, the bill amends existing defense law to completely prohibit the United States from conducting any explosive testing of a nuclear weapon or any other nuclear explosion. Furthermore, it explicitly cuts off funding for such activities from FY2026 onward.

The End of the Big Boom

For decades, the idea of nuclear testing has hung over international relations. This bill draws a hard line, stating clearly that the U.S. will no longer conduct tests that involve a full, explosive nuclear chain reaction. Think of it this way: the government can’t authorize or spend a dime of federal money on setting off a nuclear bomb, even a small one, for testing purposes, once the 2026 budget cycle hits. This move is a major signal to the global community, reinforcing the long-standing, though sometimes shaky, international moratorium on nuclear testing. For anyone concerned about global stability and arms control, this is a clear win, cementing a commitment to non-proliferation.

The Subcritical Loophole (It’s Not What You Think)

Crucially, the RESTRAIN Act is very specific about what it doesn’t prohibit: subcritical nuclear tests. The bill defines these as tests involving fissile materials that cannot sustain an explosive nuclear chain reaction. This is the policy equivalent of saying, “We’re stopping the full-scale fireworks show, but we’re keeping the lab open for highly controlled experiments.”

For the scientists and engineers who maintain the U.S. nuclear stockpile, this is a necessary distinction. Subcritical tests allow them to study the behavior and aging of nuclear materials without violating the explosive testing ban. It means the U.S. can continue to ensure the safety and reliability of its existing weapons without detonating anything, which is vital for national security but doesn't undermine the arms-control goal of the bill. It’s a smart carve-out that balances non-proliferation goals with the practical need to manage a nuclear deterrent.

Who Feels the Change?

This legislation primarily affects the defense and scientific communities involved in nuclear weapons maintenance. For defense contractors and labs that might rely on the infrastructure and funding associated with explosive testing, this represents a permanent shift toward non-explosive methods. While the allowance for subcritical testing mitigates the impact on the overall scientific mission, the full-scale explosive testing programs are officially being shut down and defunded.

For the rest of us, the impact is less about daily life and more about the global landscape. This bill reinforces the international norm against nuclear testing, potentially easing geopolitical tensions and strengthening the diplomatic hand of the U.S. in pushing other nations to adhere to similar restraints. It’s a move toward greater transparency and stability, ensuring that the U.S. commitment to arms control is backed by law and budget restrictions.