So grave was the crisis in western China that President Hu Jintao canceled a meeting with President Obama, broke off from the G8 summit and flew home.

By official count, 158 are dead, 1,080 injured and a thousand arrested in ethnic violence between Han Chinese and the Muslim, Turkic-speaking Uighurs of Xinjiang. That is the huge oil-rich province that borders Pakistan, Afghanistan and several Central Asian countries that seceded from the Soviet Union.

Uighur sources put the death toll much higher.

The Communist Party chief in Xinjiang has promised to execute those responsible for the killings.

In 1989, fear that what was happening in Eastern Europe might happen in Beijing produced Tiananmen Square. The flooding of Chinese troops into Xinjiang bespeaks a fear that what happened to the Soviet Union could happen to China. Unlike Mikhail Gorbachev, the Chinese, as they showed in Tibet, will wage civil war to crush secession.

Already, Beijing has struggled to ensure perpetual possession of Inner Mongolia, Xinjiang and Tibet -- half of the national territory -- by moving in millions of Han Chinese, swamping the indigenous peoples, as they did in Manchuria.

The larger issue here is the enduring power of ethnonationalism -- the drive of ethnic minorities, embryonic nations, to break free and create their own countries, where their faith, culture and language are predominant. The Uighurs are such a people.

Ethnonationalism caused the Balkan wars of 1912 and 1913, triggered World War I in Sarajevo, and tore apart the Austro-Hungarian and Ottoman empires. Ethnonationalism birthed Ireland, Turkey and Israel.

Ethnonationalism in the 1990s tore apart the Soviet Union and Yugoslavia, and broke up Czechoslovakia, creating two-dozen nations out of three. Last August, ethnonationalism, with an assist from the Russian Army, relieved Georgia of Abkhazia and South Ossetia.

Russia has its own ethnic worries in Chechnya, Dagestan and Ingushetia, whose Moscow-installed president was nearly blown to pieces two weeks ago and where a Chechen convoy was ambushed last week with 10 soldiers killed.

The ethnonationalism that pulled Ireland out of the United Kingdom in 1921 is pulling Scotland out. It split the Asian subcontinent up into Pakistan, India and Bangladesh. Iran, Iraq and Pakistan are all threatened.

Persians are a bare majority against the combined numbers of Azeris, Kurds, Arabs and Baluch. Each of those minorities shares a border with kinfolk -- in Azerbaijan, Kurdistan, Iraq and Pakistan.

Turkey has fought for decades against Kurd ethnonationalism.

If one were to wager on new nations, Kurdistan and Baluchistan would be among the favorites. And Pashtun in Pakistan outnumber Pashtun in Afghanistan, though in the latter they are the majority.

In Africa, the savage attacks on the Kikiyu by Luo manifest a resurgent tribalism, as did the horrors of Rwanda, where Tutsi in the hundreds of thousands were massacred by Hutu.

President Clinton may have apologized to the Africans for not sending troops to stop the genocide in Rwanda, but if the America of Obama is into interventionism to protect human rights, Africa in the 21st century should provide us plenty of opportunity.

Evo Morales in Bolivia, Ollanta Humala in Peru and Venezuela's Hugo Chavez are stoking the embers, goading the Indian populations, the indigenous peoples, to take back what the white man took 500 years ago. They have met with no small success.

The contrast between insouciant America and serious China today is instructive. China is protectionist; America free trade. China is nationalist; America globalist. China's economy is export-driven; America's base is consumption. China saves; America spends. China uses its foreign exchange to lock up overseas resources; America uses foreign aid for humanitarian assistance to failed states. Behaving like ruthlessly purposeful 19th-century Americans, China grows as America shrinks.

Where Beijing floods its borderlands with Han to reduce indigenous populations to minorities, and stifles religious, ethnic and linguistic diversity, America, declaring, "Diversity is our strength!" invites the whole world to come to America and swamp her own native-born.

Observing the lightning breakup of the Soviet Union, the Chinese take ethnonationalism with deadly seriousness. American's elite regard it an irrelevancy, an obsession only of the politically retarded.

After all, they tell us, we were never blood-and-soil people, always a propositional nation, a nation of ideas. Our belief in democracy, diversity, and equality define us and make us different from all other nations.

Indeed, we now happily predict the year, 2042, when Americans of European ancestry become a minority in a country whose Founding Fathers declared it set aside for "ourselves and our posterity."

Without the assent of her people, America is being converted from a Christian country, nine in 10 of whose people traced their roots to Europe as late as the time of JFK, into a multiracial, multiethnic, multilingual, multicultural Tower of Babel not seen since the late Roman Empire.

The city farthest along the path is Los Angeles, famous worldwide for the number, variety, and size of its ethnic and racial street gangs.

Not to worry. It can't happen here.