日本的国防姿态长期依赖一种矛盾：在强烈反对核武器的同时，却又安全地处于美国的核保护伞之下。日本防卫大臣小泉进次郎最近因建议日本应「无禁忌地讨论所有政策」而引发争议，这番言论随即遭到拥核邻国以及国内反核团体的强烈批评。

小泉的目的未必是让日本获取核武（这在政治上过于敏感），而是希望开启对1967年「非核三原则」的讨论，特别是关于禁止将核武器引入日本领土的规定。现实情况是，日本极度依赖美国的延伸吓阻能力，维持这些战后的禁忌，使得日本越来越难以解释为何在依赖核武保护的同时，却连讨论核武存在的可能性都加以拒绝。

在中国、俄罗斯和北韩不断扩充核武库的快速变化安全环境中，日本需要重新审视其自我设限的政策。首相高市早苗等人也曾暗示讨论「核共享」的可能性；归根结底，日本必须透过公开讨论来决定其政策，而不是让对外部反应的恐惧来界定甚么才可以被讨论。

Japan's defense posture has long relied on a contradiction: strongly opposing nuclear weapons while safely sitting under the US nuclear umbrella. Defense Minister Shinjiro Koizumi recently sparked controversy by suggesting that Japan should "discuss all policies without any taboos," a remark that quickly drew harsh criticism from nuclear-armed neighbors and domestic anti-nuclear groups.

Koizumi's objective is not necessarily for Japan to acquire nuclear weapons, which remains too politically sensitive, but to open a debate on the 1967 "three non-nuclear principles," specifically the rule against permitting the introduction of nuclear weapons into its territory. The reality is that Japan deeply depends on US extended deterrence, and maintaining these postwar taboos makes it increasingly difficult to explain why the country relies on nuclear protection while refusing to even discuss the possibility of their presence.

In a rapidly changing security environment where China, Russia, and North Korea are expanding their nuclear arsenals, Japan needs to reexamine its self-imposed limitations. Prime Minister Sanae Takaichi and others have also hinted at the possibility of debating nuclear sharing; ultimately, Japan must determine its policies through open discussion rather than allowing the fear of external reactions to dictate the boundaries of its debate.