Furthermore, if there are moves available to the players, so that it is an advantage to get on with the maneuver even while negotiating, and particularly if some maneuvers become visible to the other player only after a time lag, there is no reason to suppose that an instantaneous moratorium on maneuver will reign from the outset; in that case, the game progresses while the talk is going on. … One may say and say that a gun is loaded without being able to prove it until he actually shoots; one may say and say that he considers an area strategically important and not be believed until he incurs expense or risk in its protection. Thus moves can reveal information about a player's value system or about the choices of action available to him; moves can commit him to certain actions when speech often cannot; and moves can often progress at a speed that is determined unilaterally, not dependent on formalities of agreement at a conference.

Thomas C. Schelling, The Strategy of Conflict, loc. 240