Donald Trump and Vladimir Putin are fond of saying nice things about each other. And indeed, there are eerie parallels between the rise of Putin in Russia and Trump here in the U.S. But that doesn't mean 2017 will bring some creepy new bromance between Trump and Putin.

Why? Because not even President Trump can truly buddy up with the Russians.

On the level of international relations, there's a key ingredient for a chummy partnership with the U.S. and Russia that is totally lacking. And it's a big one. Put simply, the nettlesome problem is that dominating Europe remains in Russia's national interest. This is decidedly not in America's interest. And surely, even Trump knows it.

Ever since Peter the Great was determined to drag his countrymen into the modern age, and into the thick of European war and European politics, war and politics on the Continent have been stymied by the often-dark question of exactly how far west Russian interests — and control — should legitimately be allowed to extend. Today, in a sea of uncertainty and institutional weakness, it ought to come as an odd relief to see that some features of the strategic global landscape, this one included, haven't changed.

Back in the old days, a powerful Russia was seen as a fair price to pay for, say, the defeat of Napoleon. But after France's foes regained their footing, Russia's subsequent effort to supplant the Turks' Balkan Empire — and gain unfettered access to the Mediterranean Sea — was rebuffed. Moscow has always found it hard to turn down an offer to absorb parts of Poland, so when Hitler gave the Kremlin another shot, Russian intervention in Europe opened another chapter, ultimately laying the groundwork for a whole system of satellite states behind the Iron Curtain. Come 1991, the book was closed on that era. And with it, some assumed, the question of Russian influence over Europe went with it.

As Presidents George W. Bush and Barack Obama discovered, that was not to be. Russia's Europe policy has been one of steadily clawing back influence and control wherever and whenever possible. So Georgia and now Ukraine have been debased and dismembered, but not completely; Estonia has been intimidated and sabotaged with cyberattacks, but not invaded; Kaliningrad, Russia's Baltic enclave (and a testament to the country's catastrophic environmental track record since the days of communism), is chockablock with weapons designed to cow Scandinavia and daunt NATO.

And that's to say nothing of Russia's deeper subterfuge — a matter so "complex" that it's far too difficult even now for the West to grasp the specific extent and nature of Moscow's relationship to international terror. As ever, what Russia wants is a weak Europe it can dominate. For years now, that's what it's been getting.

Even under Trump, the U.S. can't protect its own core interests if it cedes Europe to Putin. Without Europe in our corner, all of liberalism's marbles would be in one basket — America's — at a moment when our shared confidence in humanism is already too shaky. We'd be more alone than ever militarily, too, a position of great peril given how thinly spread we'd be lacking any European support. Finally, rather than helping concentrate American clout for leverage elsewhere, a collapse of influence would have (Cold War nostalgia alert) a domino effect worldwide. While we reasonably fret about homegrown neo-Nazis, China is busy consolidating a truly neo-fascist regime — ethno-nationalist, corporatist, and conflict-hungry to boot — of historically unprecedented reach and ambitions. If Trump loses Europe to Russia, he would exacerbate all of these problems, no matter how inclined he might be to share some global responsibility with Russia.

Annoying as the unending political drama of Europe may be, America can't just wash its hands of the mess (a lesson President Obama should have learned on Day One of his administration, but will leave office never having mastered). Even if Trump doesn't always want to surround himself with the very smartest people, he'll soon find that, here, he's already surrounded. Even if he doesn't realize that he must stop Putin from his long-held goal of expanding into Europe, the people around Trump, and the veteran experts in America's "deep state," will absolutely know this.

If you want to make America great again, you've got to make its continental presence in Europe great again, too. However much Trump may wheel and deal with the Russians, only one country can have the upper hand in Europe — a fact that ensures he can't jump into bed with them, too.