Although their use might bring short-term tactical success, this would not be proportionate to the long-term negative effects.

 It is very hard to see how anything other than a last act of self-defence in a national war of survival could be justified in legal or ethical terms.

The use of these weapons has both short and long-term implications that must be considered before deciding if their use is proportional (for example, if the taboo over their use is broken down, what will this mean for future conflicts now that using this type of weapon is ‘normal’, would this lead to more suffering long term?).

Guy Van Damme and Nick Fotion, ‘Proportionality’ in Guy Van Damme and Nick Fotion (eds.), Moral Constraints on War, (Lexington, Lanham, 2002), p138-139.