Dual

The North Atlantic Treaty Organization (NATO) philosophy is based on promoting peace and stability and protecting the security of its members through a European and North American defence alliance. The alliance enjoys an "open door policy" whereby any European country willing to undertake the obligations and commitments of membership is welcome to apply for membership. Any decisions on expansion must be approved by a unanimous vote of the current 30 members. The essential feature of the alliance is Article 5 of the Washington Treaty on Collective Defence, which establishes NATO as a powerful alliance that guarantees security by the military response and protects any member state if it is attacked.