This policy is called Isolationism.
The first 150 years of its history the United States avoided becoming involved with other countries and this policy was called Isolationism.
Most of the country's early founding fathers believed that the United States should focus on building their own country. They believed that by being involved in the internal or external matters of other countries, the United States will always be at a disadvantage.
The policy was maintained for over 150 years after which the United States began to 'take interest' in South American countries and later all over the world in the form of World War I and World War II.