US allies face formidable technical, legal, and diplomatic barriers to acquiring nuclear weapons before 2027, underpinning the strong trader consensus against such an outcome. Existing NPT commitments, IAEA safeguards, and alliance arrangements with the United States constrain independent programs, while developing enrichment, warhead design, and delivery systems typically requires years even under accelerated conditions. Recent developments, including the September 2026 US-Saudi civilian nuclear cooperation agreement and ongoing debates in South Korea and Japan over extended deterrence, have highlighted proliferation risks and domestic support for stronger capabilities in some quarters, yet these remain centered on energy cooperation, nuclear-powered submarines, or sharing arrangements rather than weaponization. Late-breaking shifts, such as rapid Iranian advances prompting Saudi breakout or policy reversals in Seoul, represent the primary scenarios that could still alter probabilities within the resolution window.