To assess the possibility of a future denuclearized Korean peninsula it is important to consider not only US and allied security interests, but also North Korean underlying security concerns. However, beyond the North–South conflict on the Korean peninsula, there is also a longer-term problem of Korean–Japanese relations. Both Japan and South Korea have the capacity to rapidly develop and acquire nuclear weapons. North Korean nuclear acquisition could well provide the rationale for either or both to acquire nuclear weapons. In the Northeast Asian region there is already a lengthy history of denuclearization proposals and even agreements. While the focus of previous proposals had concentrated on the Korean peninsula itself, an alternative way forward would be the initial establishment of a nuclear-weapon-free zone (NWFZ) between Japan and South Korea, with North Korea encouraged to join at a later date. The negotiation of a Korea–Japan NWFZ would serve to confirm and guarantee the current non-nuclear-weapon status of South Korea and Japan, while acting as an important confidence-building step to address North Korea's underlying security concerns and enable it to subsequently join the NWFZ. Internationally, the commitment of the US Obama administration to a reduced reliance on nuclear weapons, the recent unanimous final document of the 2010 Nuclear Non-Proliferation Treaty Review Conference calling for expansion of NWFZs, and the greater openness of the USA and other nuclear powers to NWFZ establishment in areas of regional conflict, suggest that we now have a new window of opportunity for denuclearization of Northeast Asia.