It’s a tweet pinned to the top of the official account of the US State Department: "This is OUR Hemisphere, and President Trump will not allow our security to be threatened." US diplomacy is making the capture of Venezuela’s president and the threats against Greenland about security. But it was first about drugs and immigration, and now oil and precious minerals. 

Read moreTaking over Greenland, a long-standing US obsession

So what does drive this present-day version of the 19th-century Monroe Doctrine and its claim that the United States holds imperial sway over its entire hemisphere? We ask about motives and targets.

The same Trump administration that wanted to cut a quick deal with the Kremlin on Ukraine is first pressuring an ally of Moscow in South America and now defying Vladimir Putin with the boarding in the North Atlantic of a Russian-flagged ghost tanker originally bound for Caracas. What reaction can we expect from China, the main importer of Venezuelan crude?

Read moreUS military seizes Russian-flagged oil tanker in North Atlantic

And what do NATO allies make of a US that expresses support for a plan that would effectively halt Russia's advance in Ukraine, while threatening to seize Greenland from Denmark? 

Produced by François Picard, Rebecca Gnignati, Daniel Whittington, Ilayda Habip, Charles Wente.