Fortress North America is a term used both during the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...

and more often in the Cold War to refer to the option of defending

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

and the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

against their enemies if the rest of the world were lost to them. In the period up to World War II, it was associated with isolationism, particularly in the US. It was viewed only as a last-ditch option in case Europe, Asia and Africa were overrun by the fascists or Communists. At the outset of the Cold War, there were some, especially in the United States, who supported the isolationist idea of fortifying the United States and abandoning other involvements overseas or with Latin America. This option was rejected with the formation of

NATO The North Atlantic Treaty Organization (NATO, ; french: Organisation du traité de l'Atlantique nord, ), also called the North Atlantic Alliance, is an intergovernmental military alliance between 30 member states – 28 European and two No ...

and the decision to permanently station troops in Europe. During the Cold War significant planning and effort went into developing continental defense systems. Most notable were the formation of NORAD and the setting up of

radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...

lines in the Canadian Arctic. Many of those more internationally oriented were concerned that a Fortress North America (US and Canada only) strategy would lead to isolation from the rest of the world, and a strategically indefensible position in the long-term.

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