2016 Nuclear Security Summit (NSS) was recently held in Washington. This meeting was the fourth, and the last conference of NSS which began in 2010. Its goal is to keep the use of nuclear power secure. Management of nuclear fuels in each country had been prioritized.
In this summit, Japan agreed to reduce nuclear stockpiles it was storing. Most of the uranium-rich materials Japan possess will be moved to the US excepting some subjects for experiments.
USA Today: Japan agrees to reduce nuclear stockpiles
The reason Japan will drop radioactive materials is to prepare for terrorism. The likelihood that ISIS and other extremists will attack a nuclear power plant in Japan is no more fantasy. And North Korea, which is the nearest fear, is willing to develop nuclear weapons. If they get the source of the atomic bomb, the security not only of Japan but also of the world will be endangered.
Japan is one of the safest counties. Thus, it is doubtful that Japanese police will be able to address the risk of terrorism. Therefore, moving enriched uranium to the US will reduce the risk of a destructive result.
On the other hand, abandoning uranium means that Japan is less likely to invent a nuclear weapon in the future. Shinzo Abe, Prime Minister of Japan and his colleagues emphasized that Japan will never intend to develop nuclear weapons. This policy has been adhered since the WWII ended. Nonetheless, Japan still has to show the will to keep this policy.
I think Japan will never possess a nuclear weapon. Indeed, some politicians estimated the possibility for Japan to arm nuclear weapons, previously. The policy of developing atomic power was adopted in the past not only for compensating poor natural resource but also for enhancing the knowledge and technique to deal with nuclear power. And now, a few politicians claim that Japan should possess nuclear weapons.
However, it is not feasible for Japan to develop a nuclear bomb. First, most of the people hate nuclear weapons, thanks to the education policy that mercilessness of atomic bombs should be reported to descendants. Second, Japan has to drop from Treaty on the Non-Proliferation of Nuclear Weapons. Once breaching the treaty, Japan will lose the US' support regarding the supply of uranium. Moreover, Japan will be sanctioned by many countries. I do not think Japan will survive the solitude in such a situation.
For the reasons above, I was not surprised to the commitment of Abe for dropping the enriched uranium at all. But I am not sure what other countries thought. Expressing the basic principle continuously is important for a nation to get trusted by others.