I got a glimpse of the new Chinese nationalism on a train ride from Washington, D.C., to Philadelphia a couple of weeks ago.

A dozen young businessmen from China, well dressed, most speaking fluent English, were visiting factories in the United States. One 28-year-old executive at a shipyard in Jiangyin, a city near Shanghai, spoke with confidence of China’s booming shipyards, his rise from a poor farm family, his car and condo apartment, and his country’s meteoric economic growth.

Then I asked whether he was ready to fight a war with Taiwan, which China regards as a renegade province, should the island declare its independence. His answer: a swift and unequivocal “yes.”

“We think differently from you in the West,” he explained. “This is a matter of our history and honor.” In other words, an emotional commitment to Chinese nationalism trumped any practical considerations about war and peace.

I thought of this conversation as I read of the large and violent anti-Japanese demonstrations in Shanghai and several other Chinese cities earlier this month.

The Shanghai demonstrators, who besieged the Japanese consulate as Chinese police stood passively by, chanted nationalist slogans such as “Show China’s strength” and “Japan out of Asia.” Never mind that China is a country where unauthorized protests are brutally crushed (think Tiananmen Square).

These demonstrations couldn’t have taken place unless the Chinese government gave initial encouragement and let them spread. The growing size and anti-Japanese fervor of the crowds finally impelled Chinese officials to call a halt to demonstrations and block the Internet sites of the organizers.

But the government’s willingness to play the nationalist card – and the enthusiastic response of Chinese youth – should give Asians and Americans pause.

The alleged cause for the protests was Japanese government approval of textbooks that play down the atrocities of Japanese occupation forces in China in the 1930s and 1940s. China has long complained that Japan has never properly apologized nor educated its people about the atrocities. Chinese get outraged by the visits of top Japanese government officials to the Yasukuni Shrine, where they pay homage to the spirits of war dead, even war criminals.

The Chinese have some reason to be upset. I’ve been to the Yasukuni Shrine; in the adjoining Yushukan museum, Japan is portrayed as the 1930s liberator of Asia, and its brutal pillage of China is celebrated. No mention here of the 1937 rape of Nanking.

And, yes, Japan has never been as frank about its militarist past as Germany has. But textbooks are insufficient reason for China to allow mobs to attack Japanese interests.

These “days of rage” appear to be a demonstration of muscle by a China determined to be the future leader of Asia. China has opposed Japan’s bid for a permanent U.N. Security Council seat, and Chinese media rail at Japan’s supposed yen for remilitarization. But this kind of reflexive Japan-bashing by China could boomerang.

Whatever Japan’s lack of contrition, the Japanese government has been a key partner in China’s rising power. Tokyo has poured about $30 billion in low-interest loans into China to help develop its infrastructure. Japan has replaced the United States as China’s biggest trading partner and is also a huge donor of aid to Third World countries.

China complains that Japan is considering proposals to amend its constitution, which limits its armed forces to a self-defense role. But in fact the Japanese population is resolutely anti-militarist. The close defense relationship between Tokyo and Washington has made it unnecessary, until now, for Japan to think about the unthinkable – acquiring a nuclear bomb.

So far, the ugly Japanese nationalism on display at the Yushukan museum is not reflected in popular pressure within the country for military activism. On Friday, Japanese Prime Minister Junichiro Koizumi, at a meeting of Asian and African leaders in Indonesia, apologized for Japan’s Asian aggression and pledged that Japan would never again turn into a military power. But Chinese president Hu Jintao didn’t seem mollified after a private meeting with Koizumi.

Instead of provoking Japanese leaders (and public) to rethink that anti-militarist pledge, Chinese officials should be thinking of ways to reduce the growing tensions between them. Revving up nationalist passions only makes those tensions worse.