Secrecy among Friends: Covert Military Alliances and Portfolio Consistency

Scholars think that friendly nations adopt secrecy to avoid domestic costs and facilitate cooperation. But this article uncovers a historical puzzle. Between 1870 and 1916, over 80 percent of alliance ties were partially or completely covert. Otherwise, hidden pacts are rare. Why was secrecy prevalent in this particular period and not others? This article presents a theory of “portfolio consistency.†Public agreements undermine the rank of hidden alliances. A partner willing to openly commit to another country but not to you signals the increased importance of this other relationship. States pressure their covert partners to avoid subsequent public pacts. This creates a network effect: the more secret partners a state has, the greater the incentives to maintain secrecy in later military agreements. Covert alliances have a cumulative effect. In seeking the flexibility of hidden partnerships, states can lock themselves into a rigid adherence to secrecy.