In president james monroe's annual address to congress in 1823, he outlined his foreign policy. this policy has become known as the monroe doctrine. what was the main point of the monroe doctrine? a. the united states would prevent future european colonization in the western hemisphere. b. the united states was planning to take over all of north and south america. c. the united states was planning on invading great britain and france. d. the united states would end diplomatic relations with all european countries.