Nuclear weapons are weapons of mass destruction. As such, the proper means of addressing the threat they pose to humanity is to ban them outright. There is no question of regulating their use in order to minimize danger to noncombatants, as you would do with a conventional weapon.

Prohibiting the use of a weapon of mass destruction can be helpful, as in the case of the 1925 Geneva Protocol against the use of chemical and biological weapons, which played a role in keeping chemical weapons from being used in World War II as they had been in World War I. But without a prohibition on possession, there was always the risk of chemical weapons being used, as indeed they were during the Iraq-Iran War (1980-'88). The same would apply to nuclear weapons, but, as we now know, with incomparably direr consequences.

The horrific experience of World War II and the bombing of Hiroshima and Nagasaki actually pushed governments to prohibit the possession of nuclear weapons. The very first resolution of the UN General Assembly established that objective as a top priority of the international community. This was the thrust of all proposals and international efforts for the remainder of the 1940s. 

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