There is an enforcement difficulty with any agreement on reduction of values of R and B in the mutual interest; it is that each other’s values of R and B may not be observable. They depend—at least to an important extent—on the criteria that will govern future decisions, not solely on the observable, physical mechanics of an alert system. They depend on how long one will wait to be “sure,” and on what risks one will accept in an emergency. Furthermore, failure to keep the agreement, if it leads to anything, leads to war itself; so recriminations and damage suits are out of the question if our model represents all-out war rather than a border scrape or a minor transgression of one partner against another.

DEFINE: R and B seem to denote response and brinkmanship parameters; the enforcement difficulty rests on their non-observability.

Thomas C. Schelling, The Strategy of Conflict, loc. 516