Harlow Unger says that with the strength and unity of the American people behind him, Monroe could make an important decision about international relations. The issue was the rebelling Spanish colonies in South America.

The king of Spain did not want the United States to recognize the colonies’ independence. And, Spain asked European countries to help it put down the rebellions.

Britain wanted no part of the Spanish proposal. It was trading heavily with these new Latin American countries. Spanish or even French control of this area would destroy or limit this trade.

So Britain proposed a joint statement with the United States to say that neither country wanted any of Spain's territory in the New World. Britain also wanted the United States to join in opposing the handover of any of Spain's American territories to any other power in Europe.

Most of President Monroe's advisers urged him to accept the British offer. Secretary of State Adams opposed it. He did not believe the United States should tie itself to any European power, even Britain.

Monroe accepted the advice of his secretary of state. He included Adams' ideas in his message to Congress in December 1823. This part of the message became known as the Monroe Doctrine.

The president said no European power should, in the future, try to establish a colony anywhere in the Americas. He said the political system of the European powers was very different from that of the Americas. Monroe said any attempt to extend this European system to any of the Americas would threaten the peace and safety of the United States.