The humanitarian evidence can be summed up as follows:
unlike conventional weapons or other weapons of mass destruction, nuclear weapons instantaneously wipe out entire populations, level cities, and devastate the environment;
radioactive contamination from nuclear weapons causes cancers and other illnesses that can persist across generations;
the environmental consequences of nuclear war, including severe climate disruption, can lead to global famine and, in the most extreme case, human extinction;
no meaningful medical or disaster relief response to the detonation of nuclear weapons is possible.
The ban treaty should build upon the successful stigmatization of nuclear weapons by citing this evidence as the humanitarian basis for prohibition—objective two of the Pledge. A comprehensive prohibition on development, production, testing, acquisition, stockpiling, transfer, and deployment of nuclear weapons will also rule out deterrence as a rationale for continued possession by a handful of States.
Deterrence is the elephant at the negotiating table, and the legal gap can’t be fully closed without coming to terms with it. Many of the States boycotting these negotiations have said participation would call their extended deterrence relationships into question. They are right about that, but the problem is with deterrence itself, not with the process that has been established to prohibit nuclear weapons.
Anne Marte Skaland (Norway), Carlos Umana (Costa Rica), Clara Levin, and Josefin Lind (Sweden) at the ICAN campaigners meeting to prepare for the ban treaty negotiating conference
There are many valid criticisms of deterrence; two stand out from a humanitarian perspective. When—not if—deterrence fails, all of humanity will suffer the consequences. Prohibition should forbid any State from imposing that risk on the rest of us, regardless of unwarranted faith that the deterrence system will never fail.
Second, deterrence itself is a threat—backed up with the means of delivery—to inflict indiscriminate, catastrophic, and unacceptable consequences not only on an adversary, but also on the rest of humanity. From the humanitarian perspective, deterrence is nothing more than nuclear terrorism. Prohibition should forbid any State from making such a threat, regardless of the rationale.
The nuclear-armed and nuclear-reliant States recognize that a comprehensive prohibition against nuclear weapons will finally close the legal gap when it comes to deterrence. They will then have to choose between implementing the prohibition by eliminating weapons that have been declared illegal or being tagged as international outlaws.