People protest against U.S. President-elect Donald Trump as electors gather to cast their votes for U.S. president at the Pennsylvania State Capitol in Harrisburg, Pennsylvania, U.S. December 19, 2016.
Jonathan Ernst / Reuters

What happens when one unstoppable force meets another? We’ll see at the first face-to-face Trump-Putin meeting, which will probably take place in the next few months. Despite the mercurial nature of both men’s style of governance, we know at least one thing to be true about them: both have a loose relationship with the truth. They readily exploit fake news, and they believe that reality is what they say it is. Worse, both men have a strong paranoid streak, with Trump primarily seeing enemies at home and Putin primarily seeing enemies abroad. Both are also certain of their own greatness: Trump regularly asserts that he’ll be the greatest president since time immemorial, while Putin asserts that he and Russia are one and the same.

It’s hard to see how such men can come together on anything of substance. Imagine for the sake of argument that Russia and the United States do indeed share a variety of common national interests. Imagine, as well, that they hammer out a deal: the United States will do A, B, and C in exchange for Russia’s doing D, E, and F.

Given the traits that they share, a rational Trump could never believe that Putin will stick to his word, just as a rational Putin could not believe that Trump will stick to his. This would be true even if, objectively, a deal might benefit both sides: each side would stand to gain even more if it failed to do its part of the bargain while its interlocutor stuck to its own. U.S. President Ronald Reagan understood this when he famously stated that the United States should “trust, but verify” Moscow with respect to nuclear arms reductions. But nuclear weapons can be counted, and their reduction can therefore be verified. In contrast, it would be difficult to verify any Russian withdrawal of troops from the occupied Donbass, especially since Putin insists that there are no troops there at all. Likewise, Putin would have a hard time verifying that the United States really did cut all aid to Ukraine.

As such, both men would have to assume—rightly—that their interlocutor has no intention of fulfilling his part of the bargain. If both men were even marginally familiar with each other’s past behavior, their mutual mistrust could only grow. Putin has cavalierly suspended, ignored, or violated many of Russia’s international commitments, the key one being the 1994 Budapest Memorandum that supposedly obligated Russia to guarantee Ukraine’s territorial integrity and security. Meanwhile, Trump has demonstrated in his first few days in office that he intends to end America’s involvement in free trade pacts and alliances.

Complicating things even more is that there is no sovereign authority to enforce international deals. And neither man would want to call on international institutions, other nations, or alliances of nations to do so, since both of them disavow the right of those parties to interfere in their country’s internal affairs. As a result, the deal could not survive.

Since both sides would likely assume that the other would violate its commitments as soon as the ink dried, they would rationally conclude that they would be foolhardy not to violate the deal as well. Naturally, both sides would accuse the other of mendacity and of being responsible for the deal’s failure to take root. Very quickly, the initial claims of trust and friendship would be followed by accusations of bad faith. The “bromance” would end, and Russo-American relations would be worse than they were before Putin and Trump tried to outwit each other.

There is a larger moral to this story, one that relates specifically to what U.S. policy toward Russia should be. Realist analysts such as Henry Kissinger, John Mearsheimer, and Stephen Walt insist that states interact on the basis of their national interests; in that sense, their analysis seems to overlap with Putin’s and Trump’s own views of international relations. But national interests are divined by policymakers such as Trump and Putin, who have their own personality quirks, ideology, culture, and the like. We can all agree that survival, stability, power, and wealth might be defined as permanent national interests. But the real question is how to decide what those words mean, both in general and in particular circumstances.

Both Trump and Putin claim to place their countries first and to want make their countries great again. Their approach to international politics has often been called nationalist, but Lenin’s term “great-power chauvinism” could be more appropriate. Can great-power chauvinism be squared with realism? The former is rooted in a peculiar ideology and mindset; the latter purports to be an objective assessment of national interests.

In an ideal realist world, Putin would not be a great-power chauvinist committed to imperial grandeur, and Trump would not be a disrupter. In fact, the United States and Russia wouldn’t even be at odds, since Russia wouldn’t have pursued imperialist aggression in Georgia and Ukraine, and the United States wouldn’t be creating strategic disasters in the Middle East.

In reality, Putin’s Russia is a dangerous adversary. It has launched two wars already—in Georgia and Ukraine. It is also threatening to seize Belarus, rattling sabers and violating the borders of the Baltic states, and arming Kaliningrad and Crimea with medium- and long-range missiles; moreover, it has officially stated that it would use nuclear weapons in response to a conventional threat and is actively supporting anti-Western, anti-American, and anti-European parties in the West. Such activities are deeply destabilizing for Europe and the United States. Even worse than the crushing of democracy, the potential streams of refugees from Ukraine and Belarus, and the spillover of war into Poland, Finland, Hungary, and other states is the fact that Russia could soon overreach and find itself on the brink of collapse.

Vital U.S. interests are threatened by Putin—not because it is in Russia’s objective interest to threaten them, but because Putin and the regime and ideology he has created require such a hostile policy. The United States should be concerned and should attempt to prevent his aggression. Yet Trump appears to believe that Putin has been misunderstood, or that his recent aggression relates to NATO enlargement. According to that line of thinking, Putin invaded Ukraine because of some possibility of Ukraine joining NATO (a possibility that no one, either in Ukraine’s policy circles or in NATO’s, would consider realistic). If that were the case, it would follow that by defanging NATO, the United States could turn Putin pacific.

Alternatively, if one takes Putin at his word and examines the nature of his regime, one has to realize that Russian aggression is largely motivated by an imperialist ideology that serves Putin’s power and has deep roots in Russian political culture. And if one dispassionately examines the military capacity of NATO states and sees that they pose no conceivable objective threat to Russia, one may also have to realize that Putin’s invocation of the NATO threat is either a cynical ploy or the symptom of a paranoid megalomania. NATO is therefore anything but “obsolete,” as Trump calls it. The United States benefits directly from a strong and defensible Europe—as well as a strong and defensible Ukraine—because that is the only way Putin’s aspirations can be contained.

Both Trump and Putin want to make themselves and their countries number one. That is impossible. Sooner or later, U.S.-Russian relations will take a serious turn for the worse. At that point, Putin will long for the moderation and predictability of Barack Obama.