The 2015 Nuclear Non-Proliferation Treaty (NPT) Review Conference started April 27 and runs through May 22. The last review conference in 2010 reached an agreement on a final document that included 64 action plans. Action 1 was: "All States parties commit to pursue policies that are fully compatible with the Treaty and the objective of achieving a world without nuclear weapons." This means that not only nuclear weapon states but also non-nuclear weapon states such as Japan should pursue such security policies that do not depend on nuclear weapons.

Japan, as the only victim of nuclear bombings in wartime, has been a constant advocate for nuclear disarmament but at the same time has been dependent on the U.S. "nuclear umbrella," i.e. "extended nuclear deterrence." This forms the so-called nuclear dilemma for Japan. We believe it is time for Japan to solve this dilemma and fulfill the promise made at the 2010 review conference.

Has Japan taken such an initiative?

On the contrary, Japan's security policy appears to have grown more dependent on the nuclear umbrella due to the worsening security environment in Northeast Asia, in particular the increased nuclear weapon capability of North Korea.

To solve the nuclear dilemma and to improve the region's security environment, the Research Center for Nuclear Weapons Abolition, Nagasaki University (RECNA) has recently published a study report titled "Proposal: A Comprehensive Approach to a Northeast Asia Nuclear Weapon-Free Zone (NEA-NWFZ)". The proposal, which is based on excellent groundwork by Dr. Morton Halperin, calls for immediate negotiation by the participants in the six-party talks on North Korea's nuclear weapons program, aiming for a "Comprehensive Framework Agreement for Denuclearization of Northeast Asia" (CFA) to address not only nuclear weapons issues involving North Korea but regional security issues closely linked to them as well.

The CFA should contain the following four elements:

• Declare the official termination of the Korean War and provide for mutual nonaggression, friendship and equal sovereignty among CFA state parties.

Assure equal rights to access all forms of energy, including nuclear energy.

Agree on a treaty to establish a Northeast Asia Nuclear Weapon Free Zone in which Japan, South Korea and North Korea would be non-nuclear "Intrazonal States" and the U.S., Russia and China would be "Neighboring Nuclear Weapon States." The three nuclear weapon states would be required to provide security assurances not to attack the zone with nuclear weapons or, hopefully, with conventional weapons (in other words a "negative security assurance"). North Korea would also be obliged to dismantle its nuclear arsenal and related facilities within a generous time frame.

Establish a permanent Northeast Asia Security Council whose primary objective would be to ensure the implementation of the CFA and to serve as a platform for discussions involving various Northeast Asian security issues.

If such a framework agreement is attained, the nuclear umbrella will no longer be necessary for Japan and South Korea. The NEA-NWFZ, in addition to general clauses included in other NWFZ treaties, should address unique issues in Northeast Asia, including the right of states for peaceful space exploration in accordance with the 1967 Outer Space Treaty.

We understand the difficulties of concluding a CFA among the six countries amid the current security environment. But we believe such difficulties should not be the reason not to take the initiative. On the contrary, we believe pursuing a CFA, including a NEA-NWFZ, would provide a window of opportunity to improve the regional security environment.

This year is the 70th since the end of World War II, the atomic bombings on Nagasaki and Hiroshima, and the division of the Korean Peninsula. The international community, and especially Northeast Asian nations, should make 2015 the year to begin working toward achieving a CFA.

The framework would form the foundation for easing tensions and normalizing relations in Northeast Asia and for moving toward a cooperative regional security system. Japan is in a perfect position to take the initiative to propose a CFA, possibly with South Korea. We hope that the final document of the 2015 NPT Review Conference will include a sentence addressing the establishment of a NEA-NWFZ.

It is a time for Japan to solve its nuclear dilemma and thus contribute to achieving a world without nuclear weapons.

Hiromichi Umebayashi is a former director and visiting professor at the Research Center for Nuclear Weapons Abolition, Nagasaki University (RECNA).