The U.S. has maintained a moratorium on nuclear explosive testing since 1992, relying on the Stockpile Stewardship Program to certify warhead safety and effectiveness without detonations. President Trump’s October 2025 directive to resume testing “on an equal basis” with Russia and China initially raised expectations, yet subsequent administration statements clarified that only subcritical or non-nuclear experiments are under consideration, with no technical requirement identified by NNSA or military leaders for full-yield tests. The most recent development, a September 2026 underground chemical high-explosive experiment at the Nevada National Security Site, focused on refining detection algorithms for low-yield or decoupled foreign blasts rather than advancing U.S. explosive capabilities. Any actual nuclear test would face multi-month preparation timelines, congressional and international pushback, and verification challenges under existing arms control norms, keeping near-term probabilities low in trader assessments.