The court then contradicted itself by stating that while it would generally be contrary to the principles of international humanitarian law to use nuclear weapons, the Court was unable to decide whether such use would be unlawful under what it termed “extreme circumstances where survival of a state is at stake.”
The International Court of Justice did not offer any more clarity but did reaffirm that the general principles of the law of armed conflict would apply to the use of nuclear weapons.
It is important to note that these discussions mostly revolved around the use of relatively low-yield weapons according to McNamara’s vision of a controlled, managed, limited nuclear war involving the deployment of a relatively small number of low-yield weapons that would presumably result in limited collateral damage and destruction. It would undoubtedly be challenging to argue for the legality of the use of high-yield nuclear weapons on the modern, mostly urban, battlefield—or to argue for a massive nuclear exchange, which would result in vast destruction and tremendous loss of life.