Operation Active Endeavour is a maritime operation of the North Atlantic Treaty Organization. It operates in the Mediterranean Sea and is designed to prevent the movement of terrorists or weapons of mass destruction. It has also collateral benefits in enhanced security of shipping in general. It is one of the first military actions taken by NATO in response to an invocation of Article 5 of the North Atlantic Treaty which provides for collective defense and the first ever operation conducted by the Alliance in direct application of the defence clause of the Treaty.