Authoritarian powers that are fundamentally hostile to democracy cannot be ignored or appeased.

This year marks the 70th anniversary of the 1948 Communist coup in Czechoslovakia. By the time Prague fell, the Soviet Union had already forced other Eastern European countries into its orbit, in the process killing or arresting opposition leaders and crushing trade unions, churches, and other independent institutions. But Czechoslovakia, the region’s only democracy during the interwar period, was regarded as a special case.

The seizure of power in Prague shattered lingering illusions about the nature of the Soviet system and the plans of Joseph Stalin. He had already made clear that he had no intention of relaxing his regime of domestic terror. With Czechoslovakia added to Hungary, Poland, and the other satellite states, it was confirmed for all but the most naïve that Moscow was bent on a policy of relentless hostility to democracy and the creation of client states wherever the opportunity arose. No amount of diplomatic engagement or wishful thinking would alter Stalin’s course.

For many, then, the Prague tragedy marked the true beginning of the Cold War.

The question today is whether democracies have reached a similar inflection point in their relations with the modern authoritarian world, especially with its two major powers, China and Russia.

Russia has punctuated years of antidemocratic hostility with the attempted assassination of Sergey Skripal, an outrage that comes on the heels of other murders on foreign soil, the invasion of Ukraine, and the brazen destruction of a Malaysian airliner over…