The shade of Theodore Roosevelt is grinning. President Donald Trump has been holding forth about matters of geopolitical import. Some of his remarks reflect his tongue-in-cheek style. Not for nothing has the president earned the title of galactic overlord among trolls. There is no political constituency either north or south of the border for making Canada the fifty-first U.S. state. Nor is there any constituency for changing the name of the Gulf of Mexico to the “Gulf of America.” And I say that as someone who grew up alongside the Gulf. The historic name of that body of water offends no one—least of all residents of states abutting the Gulf of Mexico.

He is jesting. One hopes.

His musings about Greenland and the Panama Canal are a more serious matter. He broached a purchase of Greenland from Denmark while declining to rule out a military seizure of the island. There would be strategic logic to such a move. Greenland fronts on the Arctic, an emerging theater of strategic competition, while abutting the Greenland-Iceland-U.K. gap, Russia’s access to the North Atlantic. It abounds in critical minerals. China has been nosing around for mining rights along with its other activities as a self-proclaimed “near-Arctic” state. And then there’s the Panama Canal. Shutting the canal in times of war would compel U.S. maritime forces to default to much longer, more time-consuming, more arduous voyages to swing between the oceans. U.S. control would hold that prospect at bay.

Control of the two sites would the bolster strategic defense of the Americas.

Such worries are nothing new. In fact, some shrewd commentators have detected a Roosevelt-esque strain in Trump’s words. Not by name. But they connect Trump’s remarks to the Monroe Doctrine, an enduring theme in U.S. foreign policy ever since President James Monroe and Secretary of State John Quincy Adams codified it in 1823. Now, it’s worth pointing out that there is no such thing as “the” Monroe Doctrine. The doctrine underwent at least three phases during the century after 1823 as political and strategic circumstances changed and U.S. national power waxed. The first is what I long ago took to calling the “free-rider” phase, which spanned from the days of Monroe and Adams until the first serious U.S. Navy battle fleet took to the seas—until, say, around 1890. (Congress ordered keels laid for the Navy’s first steam-propelled, armored, big-gun cruisers in 1883.)

Why free-rider? Because America didn’t enforce its own doctrine! It let others do it. The erstwhile mother country and enemy, Great Britain, had reasons of its own for keeping rival empires from reconquering Latin American republics that had thrown off European rule in a spate of revolutions. A confluence of British power—the chief implement being the Royal Navy, mistress of the seas—with British and U.S. interests made London a silent partner in enforcing the Monroe Doctrine. The........

© The National Interest