There was only one catch and that was Catch 2012, which specified that no country was allowed to have nuclear weapons to deter its enemy's nuclear weapons unless it already had them.
The only countries that possessed nuclear weapons legally – the permanent members of the UN Security Council – did so on the understanding that they had made a solemn promise to phase them out. This they had no intention of doing.
Countries like North Korea and Israel which possessed nuclear weapons illegally did not consider themselves bound by any such undertaking – an indication of the higher moral standard to which they aspired. These countries made it very clear that they had the power to inflict indiscriminate death on the civilian population of their neighbours, and that was just fine with them.
Countries like Iran which saw themselves as threatened by weapons of mass destruction held illegally countries like Israel were, however, under no circumstances to be allowed to possess the power to deter such an attack. If they tried to do so, they were to be destroyed, even if this caused catastrophic damage to the global economy and sowed seeds of hatred for generations to come.
Some people suggested that it would be quite easy to avoid such a conflict. All that would have to happen would be for the nations that possessed nuclear weapons illegally or sought to do so to phase them out or refrain from making them in the first place, and agree to a nuclear-free regional zone enforced by intrusive UN inspections. This suggestion was greeted with enthusiasm and relief by most civilians. As the consequence it was immediately laughed at and dismissed by those who made the decisions.
(P.S. 31 Jan: Steve Coll on cool heads)