If you're looking for a place to apply the Monroe Doctrine, take a look where Venezula is getting its arms.
"In 1904, President Theodore Roosevelt added the Roosevelt Corollary to the Monroe Doctrine, which asserted the right of the U.S. to intervene in Latin America. This is the largest extension that has ever been added to the Monroe Doctrine."
It has been generally understood, since the time of Roosevelt, that the Monroe Doctrine extends to any case where a foreign state (not just European powers, as under the original Monroe Doctrine) threatens U.S. interests in the western hemisphere with regards to access to international territory.
True, there was the Clark Memorandum in 1940 (related to FDR's "Good Neighbor Policy"). However, the Clark Memorandum was subsequently nullified by subsequent U.S. interventions in the hemisphere from Eisenhower on.