Collective Security - Collective Defense

Collective Defense

Collective defense (also collective defence) is an arrangement, usually formalized by a treaty and an organization, among participant states that commit support in defense of a member state if it is attacked by another state outside the organization. NATO is the best known collective defense organization. Its now famous Article V calls on (but does not fully commit) member states to assist another member under attack. This article was invoked after the September 11 attacks on the United States, after which other NATO members provided assistance to the US War on Terror in Afghanistan.

Collective defense has its roots in multiparty alliances, and entails benefits as well as risks. On the one hand, by combining and pooling resources, it can reduce any single state's cost of providing fully for its security. Smaller members of NATO, for example, have leeway to invest a greater proportion of their budget on non-military priorities, such as education or health, since they can count on other members to come to their defense, if needed.

On the other hand, collective defense also involves risky commitments. Member states can become embroiled in costly wars in which neither the direct victim nor the aggressor benefit. In the First World War, countries in the collective defense arrangement known as the Triple Entente (France, Britain, Russia) were pulled into war quickly when Russia started full mobilization against Austria-Hungary, whose ally Germany subsequently declared war on Russia.