The claim that ambiguity can maintain peace in a crisis challenges our intuition. Ambiguous, weak, and fumbling commitments have been blamed for many wars. Most famous, perhaps, is England's vague commitment to France and Russia during the July 1914 crisis. Sir Edward Grey, British foreign minister, refused both to promise neutrality to Germany and to extend security guarantees to Russia and France beyond the loose alliance framework established by the 1904 Entente Cordiale between Britain and France and the 1907 Anglo-Russian Entente. Many claim that, at a minimum, Grey's strategy failed to prevent an avoidable escalation of conflict and may even have caused Germany and Austria, as well as France and Russia, to act on misperceptions about Britain's intentions (Albertini 1957; Snyder 1984; Trachtenberg 1991). Similarly, scholars have argued that weak third-party military commitments to European powers, especially Czechoslovakia and Poland, failed to deter Germany in 1938 and 1939 (Taylor 1961; Morrow 1993). More recently, critics have charged that mixed signals from the United States in 1990 about how it would respond to Iraqi aggression on its southern border opened the door for Saddam Hussein's invasion of Kuwait. Had the United States declared its intention to respond militarily, the argument goes, war may very well have been avoided (Jervis 1994).

Prevailing wisdom maintains that third-party defenders have the best shot at reducing misperception and war if they extend strong, well-defined public pledges of military support to their allies (Fearon 1997; Huth 1999; Schelling 1960; Zagare and Kilgour 2000). However, governments often do not fully flesh out the details of many commitments, including formal military alliances. Of 259 alliances formed between 1816 and 2000 and designed to deter threats to allies, 74 promised to defend the ally no matter what, 139 conditioned third-party intervention on the initiation of conflict by a non-alliance member, and 46 were “ambiguous” in that signatories did not have automatic contractual obligations to intervene on behalf of fellow alliance members in war.