NATO is an international military alliance that consists of 30 member states from Europe and North America. It was established at the signing of the North Atlantic Treaty on 4 April 1949. Article 5 of the treaty states that if an armed attack occurs against one of the member states, it shall be considered an attack against all members, and other members shall assist the attacked member, with armed forces if necessary. Article 6 of the treaty limits the scope of Article 5 to the islands north of the Tropic of Cancer, the North American and European mainlands, the entirety of Turkey, and French Algeria. As such, an attack on Hawaii, Puerto Rico, French Guiana, Ceuta, or Melilla, among other places, would not trigger an Article 5 response.