At the 2014 Nuclear Security Summit that just concluded, Japan announced that it would return some 500 kilograms of weapons-usable material, highly enriched uranium (HEU) and plutonium, that it has had at a research facility to the countries that supplied it.

This is the single largest repatriation of material that has resulted since the Nuclear Security Summits began in Washington in 2010. The material Japan is returning is enough for 50 to 70 nuclear weapons.  

Last month, Chinese officials hinted that Japan was resisting efforts to repatriate such materials. At a press briefing on February 17, China's foreign ministry spokeswoman stated that "China has grave concerns over Japan's possession of weapons-grade nuclear materials [...] Japan's failure to hand back its stored weapons-grade nuclear materials to the relevant country has ignited concerns of the international community including China."

Japan's announcement Monday is a big win for the Hague summit, but its half-ton of material is a drop in the bucket compared to the amount of fissile material still out there: 1390 tons of HEU and 490 tons of separated plutonium that are enough for more than 100,000 weapons.

This is 30 percent more than the US and Russian stockpiles at the height of the Cold War. Half of that material is in military stockpiles and countries should renew their attention to efforts to eliminate that material.

In that light, Japan's material is not the biggest problem. If there is any message to be taken away from the summit, it is that we are only as secure as the weakest link. 

China is correct in bringing attention to this issue and Japan is doing the right thing by returning the material. Bigger issues in nuclear security loom for both, however: how they handle plutonium in their civil nuclear energy programs.

The future of nuclear energy, particularly in Asia, needs to address what happens with spent nuclear fuel; how to store it, dispose of it, or if recycling it, how to minimize the security risks associated with separating it, fabricating it into fuel and burning the fuel in reactors.

Japan made reprocessing of spent fuel an integral part of its peaceful nuclear energy program. But does this still make sense after the March 2011 Fukushima Daiichi nuclear accident that triggered a shutdown of all Japanese power reactors?

Without a clear path for using the separated plutonium in reactor fuel, starting up the Rokkasho-mura reprocessing plant this year will increase the stockpile of separated plutonium with nowhere to go.

The draft of the Japanese Basic Energy Plan indicates a "business as usual" approach to Rokkasho and other fuel cycle facilities, despite the fact that it is unclear how many nuclear power plants could ever be restarted.

For China, which has reprocessed spent fuel for nuclear weapons and is now considering doing the same in its civilian nuclear energy program, the question is not just a matter of economics but also security. Reprocessing is an expensive and risky detour.

Added to this mix is the other civilian nuclear powerhouse in Northeast Asia, South Korea. South Korea has convinced itself it needs to match Japan and China in this area and is seeking both enrichment and reprocessing capabilities in the future. Clearly, a regional dialogue is needed to head off tensions in yet another sensitive area.

Japan, China and South Korea should take this 2014 Nuclear Security Summit as an opportunity to assess the nuclear security risks that their civilian nuclear energy programs may pose in the region, work with others on collaborative approaches for reducing risks, and above all, enhance transparency among the parties to build confidence in nuclear energy and nuclear security going forward.

The author is a senior fellow and director of Proliferation Prevention Program, Center for Strategic and International Studies. opinion@globaltimes.com.cn