Article 5 of the Washington Treaty, NATO's founding document, has long been considered the glue that has held NATO together and made it one of the most successful alliances in history. It is the key article of the Treaty, in which members pledge to come to each other's aid in the event of an attack. When NATO faced Warsaw Pact armies across the Fulda Gap during the Cold War, everyone understood what Article 5 implied.
But today it is less and less clear. One NATO ally, Turkey, has sought to invoke Article 5 twice during the last war in the Persian Gulf and has been rebuffed by allies both times. Following the terrorist attacks of September 11, 2001, NATO invoked Article 5 to show solidarity with the United States, but Washington declined the offer. When Estonia experienced a cyber security attack in June 2007, most allies were bewildered about what, if anything, to do. U.S. Senator Richard Lugar has suggested that a cutoff of energy supplies by a country like Russia to a NATO ally could be seen as the equivalent of an Article 5 attack. In Central and Eastern Europe, where fears about Russian power and intentions remain very real, the lack of any NATO deployments, military planning, or exercises to balance a more assertive Moscow have led some politicians to publicly declare that Article 5 has become hollow.
In an alliance that is larger and facing more and diffuse threats that affect some members more than others, how should NATO countries consider Article 5?
How should Article 5 factor into NATO decision-making as the alliance considers new members and new missions?