North Atlantic Treaty Organization more commonly said NATO is responsible for mutual defense and The United state is a founding member of this organization.
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What is the main purpose to establish NATO?</h3>
North Atlantic Treaty Organization was established in 1949 by the USA, Canada and some European countries to provide the securities to NATO members against the USSR.
At present time there are 30 members from Europe, North America, and Asia. Its headquarters is located in Brussels. USA leads this organization because he is a major contributor to NATO.
Therefore the correct option is D.
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