What did Monroe Doctrine state and how did this eventually relate to imperialism

The Monroe Doctrine sees the New World and the Old World as very different and each should conduct its affairs without interference from the other side. It states that the United States will not accept the intervention or colonization of American nations by European powers, and that any such act would be seen as a hostile act and a security threat to the USA. On the other side, the US would not intervene in the affairs of Europe. The doctrine was born after a speech delivered by president James Monroe in Congress in December 1823.

When the USA became a global economic power and when it developed a powerful navy and military, the Monroe Doctrine was used to justify US military interventions and political meddling in the countries of Latin America and the Caribbean in the 20th century. It has been used to legitimize American hegemony in the Western Hemisphere.