If, there is an immediate threat to those one is committed to protect, under the laws of self defence one is legally authorised to use the minimum force available to achieve that aim. If the minimum force available is a fleet of cruise missiles, then hitting the attacking threat before that threat is realised, is within the laws of self-defence. The green card we were issued with was an attempt to quantify the laws of self-defence, but has led to confusion as to when pre-emptive action in self-defence is allowed. If there is a genuinely held belief on the intelligence available at the time, that attacking the confirmed preparation of a nuclear launch by the enemy is the only way to prevent that attack, then that is well within the .definition of pre-emptive self-defence, provided the force used is proportionate and not excessive. EG ."Why, submarine commander, did you launch 25 cruise missiles at that launch site?"" "Because Admiral, I did not have 26 missiles in my magazine" is not a good defence!.