Dr Julian Lewis: I acknowledge the hon. Gentleman's [Harry Cohen's] long and consistent commitment to unilateral nuclear disarmament by this country, but let me give an example that shows that matters are not as simple as he thinks. Imagine two nuclear powers, one of which has the capability only to retaliate using large strategic nuclear weapons against cities, and the other the capability to initiate a much more precise and accurate attack against troop and military formations. Does the hon. Gentleman accept that, unless the systems are balanced, there is a danger that one of those nuclear powers might think, wrongly, that it could attack troop concentrations with impunity, because the other side would not retaliate in the only way that it could, against cities, and thus risk losing cities in return? The situation is not as simple as he suggests.