  There is a general and acknowledged difficulty in explaining how coercion by threat is possible: if the coercee defies the demand backed by the threat, it is typically irrational, because futile, for the coercer to go ahead and execute his threat. In some cases, this problem is solved by the fact that the coercer gains reputational benefits by executing the threat, or the coercer enjoys a sufficient advantage in power that executing the threat may be a relatively trivial matter for him. But coercion is a different and much more complicated matter when executing a threat is much more costly to the coercer than is the mere making of the threat. The threat of massive retaliation in response to a nuclear attack is a paradigmatic example of a kind of threat that would be irrational to execute after the associated demand is defied — if, for instance, one has already been the victim of one's opponent's first-strike. For this reason, the ability to make such a threat credibly requires more than a simple intention and ability to execute the threat, but rather a whole system that effectively removes decision from the process (by, say, building redundancy and automation into it). So, it would appear that nuclear deterrence cannot be an ordinary species of coercion, since the coercer cannot remain at liberty with respect to whether or not it will execute the threat. (For the difference this makes, see DeRose 1992.)