Recently, Peter Beinart made a case for realist internationalism in The Atlantic. In his essay, he goes after Trump’s unilateralism and trashing of core American alliances. But his major complaint is with what he calls American overreach, including the assumption that the “unipolar” moment of unchallenged American power after the collapse of the Soviet Union can or should be sustained.

Beinart pushes a more modest foreign policy. So far, so good, but his specific prescription demonstrates the weakness of realism taken as a strategic doctrine: He suggests a spheres-of-influence system in which the great powers, including Russia, China, and the United States, each get their piece of the world and respect the others’ pieces. Russia gets eastern Europe, with Georgia and Ukraine both “neutral” (like Finland and Austria during the Cold War); China gets to occupy Taiwan and dominate Vietnam, and achieves recognition of its claims in the South and East China Seas; the U.S. gets the Western Hemisphere.

As an abstraction, spheres-of-influence arrangements have appealed to foreign-policy theorists for a long time (e.g. Henry Kissinger and Walter Lippmann, 20th-century America’s most important foreign-policy journalist, whom Beinart cites). In practice, they don’t work out so well. For one thing, they usually involve doing deals with dictators at the expense of other people. Quite apart from the moral problem, for that reason spheres of influence are not stable: History suggests that autocratic great powers will never be satisfied with wherever the line is drawn.

In addition, the millions of people subject to somebody else’s arrangement (the Poles in 1945 and the Ukrainians and Taiwanese) may not accept their allotted fate. Why should they? Communist rule in Poland and elsewhere in Central and Eastern Europe during the Cold War, and Russian domination in Ukraine until 2014, meant repression and poverty. Being in a Russian sphere of influence is not like being in the EU. It’s like being in the Soviet bloc. If given to Russia’s or China’s control, the people in subject nations are likely to revolt against the resultant miserable conditions. When they do, or when the security services start their roundups of independent thinkers, should the U.S. response be indifference, pursuant to its deal with China or Russia?

The U.S. was not willing to risk war against the Soviet Union when Moscow put down the Hungarian Revolution in 1956 and the Prague Spring in 1968, or when it pushed Poland’s government into imposing martial law in 1981. But war or nothing were not the only choices.

Starting in the Carter administration and much more under President Ronald Reagan, the U.S. supported democratic dissent in the Communist bloc, including Poland’s Solidarity trade union. Reagan especially was unwilling to accept the “realist” axiom that the U.S. should tacitly accept Moscow’s sphere of influence in the eastern half of Europe. With American support, the people of those countries overthrew communism and helped end the Cold War on American, Western, and democratic terms. Following the collapse of the Iron Curtain, the U.S. and its Western Allies welcomed the liberated nations of Central and Eastern Europe into NATO and the European Union, bringing 100 million people into an undivided Europe. (Thus they achieved America’s World War II objectives: to see the Atlantic Charter signed by Roosevelt and Churchill in 1941, which made no mention of spheres of influence either with Stalin or anybody else.)