The neologism goes back to a journalist from the “New York Post”. Trump liked the formulation so much that he incorporated it into his rhetoric, as it combines his first name (Donald) and his historical role model when it comes to the “America First” agenda (Monroe). The Donroe Doctrine states, among other things, that all activities by actors outside the US sphere of influence that run counter to their own interests should be viewed as malicious. Whether these are governments that are practically on our doorstep, like Venezuela, or China, Iran and Russia.
And maybe soon Greenland too? As Trump said on board the presidential plane on Sunday: “Let’s talk about Greenland in 20 days.”
