Trump clearly views the Western Hemisphere as a sphere of exclusive American influence. Some commentators argue that he is just following the Monroe Doctrine. Is that true?
The Monroe Doctrine was an expression of American desire to prevent reactionary post-Napoleonic European regimes–primarily Spain–from throttling revolutions in South America. The US did not have the strength or the will to do this on its own, let alone dominate South America by itself. The hard work there was actually done by the British fleet. In fact, in some ways the Monroe Doctrine was a sympathetic reaction to British attempts to maintain the South American markets won during the recent war.
Conditions are much different today. The US is the greatest military power in the world. Trump doesn’t simply seek to keep foreigners from dominating the rest of the hemisphere, as Monroe did; he wants to dominate it himself. That may be a logical application of the Monroe Doctrine to changed circumstances, but it isn’t the same thing at all.