For the first 150 years of its history, the united states avoided becoming involved with other countries. what is this policy called? radicalism nationalism internationalism isolationism

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The correct answer is Isolationism

Becasue isolationism is where a country does not let anyone in or out of its borders and it does not participate in worldly afairs. It also has isolation in the name and the definition of isolation is the process or fact of isolating or being isolated.  

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mythology i believe

it proved indian land claims were unjustified.