The villains of this book are Xi and Vladimir V. Putin, who “have enough power and ambition to undermine the entire global liberal order.” Repeatedly quoting from the Cold War strategist George F. Kennan, Diamond advocates a military buildup to thwart Russian or Chinese aggression. Unless American and European democracies get their acts together, he warns darkly, the European Union and NATO might collapse, a “Greater Russian Empire” could rise as the heir to the Soviet Union and China would threaten the freedom of democracies across Asia — all resulting in “depths of oppression and aggression that we have not seen since the end of World War II.” I like a worst-case scenario as much as the next fatalist, but this passage underplays what Diamond writes sensibly elsewhere about how dictatorships misjudge, overreach and provoke blowback.

Diamond sounds klaxons that “China seeks hegemony over all of Asia and the Pacific” and “aims to dominate world politics” in this century — assertions that even some hawkish China experts would dispute. No doubt China is a fast-rising military and economic power, beefing up its naval forces, reviving nationalistic quarrels with Japan, staking expansive claims and brazenly building artificial islands in the South China Sea. But while Russia recently invaded Georgia and Ukraine, some Chinese elites seem more cautious: China hasn’t fought a real war since 1979. An actual Chinese drive for hegemony over Asia would spark major confrontations with Japan, India, South Korea, Taiwan and other regional powerhouses, as well as the United States. Diamond needs to argue harder for his hard line.

For Diamond, the United States remains, as Bill Clinton proclaimed in his second Inaugural Address in 1997, “the world’s indispensable nation.” He properly highlights how the United States contributed to democratization in numerous countries. Yet “Ill Winds” does not dwell on how the United States has blighted its democratic credibility, gliding past a darker history that could reappear during future contests against China or Russia: how the Cold War drove Washington’s support for vicious anti-Communist governments in Indonesia, Pakistan, South Africa, Argentina, Iran and elsewhere.

Today Trump fawns over Putin, Kim Jong-un, Mohammed bin Salman and other thugs, driven less by realpolitik necessity than by personal affinity. After just one year of Trump’s presidency, a Gallup poll found that the median approval of American leadership across 134 countries had cratered to just 30 percent — four points below that of George W. Bush in his last year, which priced in the Iraq war. If the universal principles of liberal democracy are going to be revived, that will require not just American renewal under a less squalid president, but the leadership of a multitude of free republics spanning India, Japan, Germany, South Korea, France, Britain and South Africa.

Whether in Taiwan, Mongolia or Ghana, people like their rulers to be lawful, accountable and disposable. Dictatorships will always have to fear their people as they get richer and better educated; tyrannical regimes can always splinter; and courageous opposition leaders will always rise up (though not, it would seem, in the Republican Party). Before dying of cancer in Chinese state captivity, Liu Xiaobo, the Nobel laureate and democracy activist, wrote that “although people must still deal with tyranny and the suffering that it causes, they can respond to hate with love, to prejudice with tolerance, to arrogance with humility, to degradation with dignity and to violence with reason.”