Beware aggrieved empires

China sent 71 aircraft and seven ships toward Taiwan in a 24-hour period, while Russia shelled the Kherson region more than 70 times.

These acts of aggression -- occurring 5,000 miles apart, one in a grinding war of attrition, the other as part of an ongoing political and diplomatic struggle that may well result in open hostilities -- are related.

It's no accident that the two most dangerous powers in the world, China and Russia, are aggrieved empires seeking to right what they consider the wrongs that resulted in their humiliation and diminishment in the 19th and 20th centuries.

Whereas in the 2000s the most pressing problem of the international system seemed to be malicious subnational groups operating in ungoverned spaces, now it is malicious would-be supranational entities seeking to take over spaces governed by others.

In his masterly book, "Diplomacy," Henry Kissinger observed, "Empires have no interest in operating within an international system; they aspire to be the international system."

The fall of the Roman Empire was a social and economic catastrophe for the West, but it's been a blessing that no such overawing behemoth ever rose in its place.

Russia and China, in contrast, never lost their imperial DNA, and have chips on their shoulders.

Russia achieved some success in its long-running ambition to be considered a major European power through top-down reforms and military conquest. It gobbled up an estimated 50 square miles a day across a couple of centuries. But it lost the Crimean War in the mid-19th century, suffered a humiliating defeat at the hands of Japan in 1905, and then experienced utter cataclysm in World War I.

Marxism-Leninism was supposed to provide a way for backward Russia to leapfrog the West. That didn't happen, but Moscow established a new Communist empire of considerable extent. Of course, this came a cropper with defeat in the Cold War, an event that Vladimir Putin, notably, considers "the greatest geopolitical catastrophe of the century."

The man who has statues of Peter and Catherine the Great, accomplished Russian imperialists, on display in the Kremlin considers an independent Ukraine merely a tool of hostile Western forces and a wayward part of Greater Russia. Such ideas -- and a deep feeling of shame at Russia's fall -- justify the brutish attempted occupation and dismemberment of Ukraine, a cynical and crude operation even by Russian standards.

If Russia sought to be a respected member of the European club, China believed it needn't bother. It was the Middle Kingdom, the only civilization in a world of barbarians who owed it tribute and deference. Its sense of superiority was punctured by the Opium Wars in the middle of the 19th century and, as with Russia, a shocking defeat in a conflict with Japan.

Eventually, China, too, turned to Marxism-Leninism. After yet more humiliation and failure, the CCP now is fired with audacious visions of a return to imperial grandeur.

President Xi Jinping is more or less explicit about it. He has said that "since the Opium War of the 1840s the Chinese people have long cherished a dream of realizing a great national rejuvenation." Now, it is on the cusp of providing "a new option for other countries," and "a Chinese approach to solving the problems facing humanity." In short, "it will be an era that sees China moving closer to center stage."

This is a vision of Middle Kingdom redux, although couched in bloodless phrasing.

Xi views Taiwan much the same way as Putin views Ukraine -- it rightfully belongs to China, and retaking it will help salve the geopolitical and psychological wounds of imperial China's spectacular descent into disaster and powerlessness. "We cannot lose even one inch of the territory left behind by our ancestors," Xi told a U.S. official in 2018.

The war in Ukraine shows that when an autocrat ruling a once-great empire speaks in such terms, it is time to arm the targeted state to the teeth and dispense with all illusions.