Document 4 This is an excerpt from the North Atlantic Treaty, which was signed by the United States, Canada, and ten nations of Western Europe in 1948.
The parties agree than an armed attack against one or more of them in Europe or in North America shall be considered as an attack against them all. They agree that if such an armed attack occurs, each of them will assist the party or parties so attacked. Each will immediately take whatever action it considers necessary to restore and maintain the security of the North Atlantic area. It will, if necessary, use armed force.
What is the purpose of NATO?