The emerging changes in the security calculus within the Korean Peninsula are forcing Japan to revisit its existing position on the nuclear issue. The changing security environment has triggered several debates within Japan on the nuclearisation of the island nation. Although, at present, domestic opinion within Japan is opposed to exercising the nuclear option, there has been a break in the hitherto established taboo to have an open debate on the country’s nuclear policy. These debates have triggered thinking on the circumstances in which Japan might choose to cross the nuclear rubicon.