The possibility of former US allies seeking their own nuclear defenses, given Washington's unpredictability under Donald Trump, is now part of political discussions in countries like Germany, Poland, Japan, and South Korea.
For the first time in decades, governments historically protected by the US nuclear umbrella are reassessing this reliance. This shift is fueled by actions from the Trump administration, including suspending arms to Ukraine and restricting intelligence sharing.
Poland's Prime Minister Donald Tusk is considering a nuclear agreement with France or pursuing its own nuclear weapons. In Asia, South Korea is openly discussing the need for a "nuclear latency" posture. Influential figures in Tokyo are debating whether Japan should develop an independent deterrent.
This global reassessment is driven by concerns about the reliability of US security commitments. European countries are realizing they need to be more autonomous, especially in sensitive military areas. While no country has yet withdrawn from the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), some are considering infrastructure that would enable rapid nuclear weapons production.
Proliferation among US allies could increase global tensions and trigger a new arms race. The period between announcing the intent to develop nuclear weapons and obtaining a functional arsenal would be particularly dangerous. Even if a future US president tries to restore ties with allies, the question remains whether that commitment will continue with each American election.
It would take at least a decade for European countries to fully replace the US nuclear shield. Therefore, developing a plan B is seen as essential for strategists in Europe, Tokyo, and Seoul.