The Problem: Overcoming the "Doctrine of Nuclear Deterrence"
Last April in his Prague speech, US President Barack Obama significantly changed the direction of US nuclear policy. Until then US government nuclear policy also considered the first use of nuclear weapons, but it would now work toward a "world without nuclear weapons" as the moral responsibility of a nation which had used them. This is a welcome change. Yet, although the US has embarked on reducing its nuclear arsenal, it maintains "nuclear deterrence" for the security of itself and its allies. It has not abandoned the political and military need for nuclear weapons.
Meanwhile, the government of Japan, which is the world's only nuclear-bombed country, has stated that its goal is to abolish nuclear weapons, but at the same time it maintains that Japan's security is preserved by the US nuclear umbrella. The Japanese government's attitude is that in order to counter threats from other countries (such as North Korea), it wants to keep the option of retaliating against attacks with conventional weapons as well, and therefore does not want to remove the nuclear umbrella.
Although both the US and Japanese governments talk about things like "a world without nuclear weapons" and "abolishing nuclear weapons," they continue taking the position that nuclear weapons are indispensable to their own security. Such policies are logically contradictory because they express the desire to eliminate nuclear weapons while at the same time committing their national security to them. Bringing about a world without nuclear weapons requires overcoming "nuclear deterrence," which implies the political and military necessity for nuclear weapons. The problem is what is needed to overcome nuclear deterrence. Here I (1) describe the characteristics of nuclear deterrence, and then explore the (2) inhumanity and illegality of nuclear deterrence and (3) the irrationality of nuclear deterrence.

Characteristics of Nuclear Deterrence
The theory of nuclear deterrence is that using this threat: "If you attack our country militarily, we'll counterattack with nuclear weapons, and your country will sustain severe damage, so you'd better give up idiotic ideas like attacking our country" will deter other countries from attacking. In this theory, nuclear weapons are a tool that deters war. As such, here I want to separately consider the issue of whether threats with nuclear weapons are permissible if the purpose is to deter war, and the issue of whether nuclear weapons are an effective war deterrent. The reason for treating them separately is that they inhabit different areas: the former is a matter of how we should see threats with nuclear weapons in humanitarian terms, and in terms of international humanitarian law (the laws of war), while the latter is a matter of rationality in terms of whether nuclear weapons are useful as a war deterrent.

The Inhumanity and Illegality of Nuclear Deterrence
We know from the experience of Hiroshima and Nagasaki what nuclear weapons bring upon humans. The atomic bombs brutally killed and injured many people indiscriminately, without distinguishing between combatants and noncombatants, and their harmful impacts linger even now, 65 years after the bombings. Humanity has established rules (international humanitarian law and the laws of war) which even at the time of war require distinguishing between military personnel and civilians, which require distinguishing between military and non-military facilities, which which ban the use of cruel weapons and the like because they are inhumane. In light of international humanitarian law, using nuclear weapons and threatening to use them are illegal. The 1996 advisory opinion by the International Court of Justice made this clear and the recent NPT revcon spoke of the "catastrophic humanitarian consequences of any use of nuclear weapons," and reaffirmed "the need for all States at all times to comply with applicable international law, including international humanitarian law." Because the use and threat of nuclear weapons are inhumane, they violate international humanitarian law. Using the threat of indiscriminate, mass, and cruel killing to carry out a state's will externally and politically is in fact illegal even if one does not use nuclear weapons.

The Irrationality of Nuclear Deterrence
The doctrine of nuclear deterrence says that nuclear weapons are meant to deter war. Do nuclear weapons really deter war? To begin with there is the historical fact that war has not disappeared from Earth since nations started developing and using nuclear weapons. Even now wars continue in Iraq and Afghanistan, and there are still tensions on the Korean Peninsula and in the Middle East. Nuclear weapons are not deterring war. And if we grant for the sake of argument that nuclear weapons do deter war, surely their possession would be encouraged, and there would be no reason to ban them. Further, instead of nuclear powers blocking the proliferation of nuclear weapons, they should give them to other countries. The reason nuclear powers don't do this is because they know well that nuclear weapons are not a means of deterring war. If war would disappear from the Earth by having all countries possess nuclear weapons, it would not be necessary to seek a "world without nuclear weapons." Claims that nuclear weapons are a tool for war deterrence are nothing but the propaganda of bad-natured politicos or the absurd babbling of war addicts. We must break free of the doctrine of nuclear deterrence.

Let's Develop Security Policies Not Dependent on Nuclear Deterrence
Bringing about a world without nuclear weapons requires creating not only the political will for it, but also the legal systems. We must quickly launch negotiations for a nuclear weapons convention, expand nuclear-weapon-free zones, and hurry the enactment of "non-nuclear laws" in all countries. I shall treat this subject in another paper.