Question

Why would Monroe decide to issue the Monroe Doctrine alone even though Britain offered to issue a joint statement?

Answer 1

United States President James Monroe enacted a law to oppose European Colonialism in the America's.

Explanation:

No.1. U.S. President  opposed the spread of colonialism in the United States and its periphery.

No.2. In this case, United States would try to appear as a stronger world force and place it at an important place in the world.

No.3. United States planned to use British military assets and personal for blocking other European powers from grabbing power in the U.S. This would eventually make the U.S. military gradually into a world class one.