The third nuclear test conducted by the Democratic People's Republic of Korea created greater "shock waves" than the second. That is because many nuclear experts suspect the DPRK might have tested a bomb small enough to fit on Unha-3, the carrier rocket it launched in December to successfully put a satellite into obit.

Some countries, especially the United States, the Republic of Korea and Japan, fear that the DPRK would soon be able to fit nuclear weapons on missiles and threaten their security. Indeed, the DPRK has threatened to launch "pre-emptive" nuclear strikes against the US, the ROK and Japan.

In the face of the DPRK's nuclear threats, many people (politicians included) in the ROK and Japan feel the need to strike a "balance of terror" by developing their own nuclear weapons. Seoul and Tokyo may face great hurdles to develop nuclear arms, but the very fact that they have felt the need for it is worrying, because it could trigger a nuclear arms race in the region.

Of course, Japan and the ROK have to get the nod from the US and the international community before developing nuclear weapons. They also have to withdraw from the Treaty on the Non-Proliferation of Nuclear Weapons giving a very strong reason for doing so. The NPT says: "Each party shall in exercising its national sovereignty have the right to withdraw from the Treaty if it decides that extraordinary events, related to the subject matter of this Treaty, have jeopardized the supreme interests of its country."

The international community, however, will never accept the withdrawal of the ROK and Japan from the NPT to develop nuclear weapons, because it could trigger the collapse of the global nuclear order established by the treaty with disastrous consequences. Moreover, the ROK and Japan will break the US-led global framework and undermine Washington's presence in the Asia-Pacific region if they develop nuclear weapons. Therefore, instead of giving the nod to the ROK and Japan, the US will take measures to thwart their nuclear ambitions. But since the nuclear threat felt by the ROK and Japan is real, the US has to ensure their security.

The DPRK's nuclear program has entered a critical stage, and it is bound to conduct more missile and nuclear tests, for it seems determined to become a nuclear-weapon state. That is to say, the DPRK will continue pursuing its nuclear-arms program, because it considers it a deterrent against countries such as the US, the ROK and Japan. Under such circumstances, if Japan and the ROK do not get reliable security guarantee, they could be forced to develop nuclear weapons even at the risk of antagonizing some countries.