In 1796, George Washington used his farewell address to plead with his countrymen to stay out of European quarrels. Europeans, he said, would forever be killing each other; the young American republic had no reason to bleed for their disputes. That instinct — non-entanglement in Europe, but active dominance closer to home — has been closer to the American default across two and a half centuries than any brief Atlanticist chapter. Tim Marshall's point is that today's Washington is not inventing a new doctrine so much as returning to the older one. The oceans still make the United States safe from any conceivable land invasion, and its two neighbours — Canada to the north, Mexico to the south — are neither militarily nor demographically capable of threatening it. The natural American obsession is the hemisphere, not the continent across the sea.
In December 1823 James Monroe warned the European powers: no further colonisation or intervention in the independent nations of the Americas. Two centuries later, the doctrine is being restated for the current administration in language its critics call the 'Don-roe' Doctrine — the same map, updated for a new set of great-power rivals. Where Monroe told the Europeans to stay out, the modern version tells the Chinese, Russians and Iranians to stay out. Chinese investment in Latin American ports and mines, Russian intelligence operations, and Iranian and Hezbollah networks operating out of Venezuela are all read in Washington as violations of the same rule: no rival great power in the hemisphere, ever.
Venezuela has the largest proven oil reserves in the world, and for decades most of Cuba's energy — around 90% at its peak — came from Venezuelan crude, shipped on preferential terms in exchange for Cuban doctors and intelligence officers. When Washington moves against the regime in Caracas, three things happen at once: the US takes a shot at controlling a huge oil reserve, it starves the Cuban government of its lifeline, and it disrupts the Hezbollah and Iranian networks that have used Venezuela as their main South American hub since the 1990s. The 'drug and criminal' language in Trump-era statements is real, but the geopolitical logic underneath it is at least as important. Marshall's framing: none of this requires you to like the policy — it requires you to see it clearly.
Since roughly 2005, China has become the largest trading partner of most South American economies. It buys Argentine soy and lithium, Chilean copper, Brazilian iron ore and Venezuelan crude, and finances ports and railways from Peru to Jamaica. From Beijing this is straightforward diversification of supply. From Washington, applying the Monroe frame, it is a rival great power planting infrastructure in the American backyard. This is why the Panama Canal keeps returning to US political rhetoric, why Chinese-financed ports in Peru (Chancay) and El Salvador attract so much attention, and why sanctions and tariffs are being used not just as economic tools but as levers to force Latin American governments to choose sides.
The southern border of the United States is not, in the Trump-era reading, primarily an immigration issue — it is a national-security perimeter. Cartel violence, fentanyl flows and mass migration are treated as symptoms of a broader loss of control over the hemisphere, and the response is designed to look overwhelming: military deployments, tariff threats against Mexico, pressure on Central American governments to hold migrants further south. Whatever one thinks of the ethics, the geopolitical logic is coherent. If your doctrine says no rival great power in the hemisphere and no hostile flow across the border, then you build the wall, you tighten Mexico, and you make examples of Cuba and Venezuela. The map is doing the arguing.
Put it all together and a coherent Latin American strategy emerges. Deny China access to critical minerals and ports. Break the Venezuela–Cuba–Iran axis. Harden the southern border. Restate Monroe loudly enough that everyone hears it. This is not a departure from American tradition — it is a return to it. The unusual period was the post-1945 decades in which US attention was pulled to Europe and East Asia by the Cold War and its aftermath. Marshall's dry observation is that once that pressure eased, the underlying geography reasserted itself. The Americans are not becoming isolationist. They are becoming hemispheric.