For Japan, the episode has fanned growing fears here that an increasingly powerful China will become ever more insistent in pressing territorial claims against its neighbors, and in trying to assert military control of ever-wider swaths of the waters around China. This anxiety has been one reason that Japan’s year-old Democratic Party government, now under the newly re-elected prime minister Naoto Kan, toned down its calls for an East Asian community, and instead has sought to strengthen ties with Washington, its longtime protector.

Concern that Chinese pressure on Japan’s borders will only grow has led to uncharacteristically strident calls in normally passive Japan to stand up to China’s demands. Japanese news media have warned of a broader pattern of China’s pushing its territorial claims, including recent disputes with Southeast Asian countries over the South China Sea.

“If China thinks that by taking a strong stance that Japan will just roll over, then it is mistaken,” said an editorial in the Yomiuri Shimbun newspaper, Japan’s largest daily.

For its part, China tends to see Japan as a proxy for the United States, whose cold-war-era alliances with Japan and other countries in the region now seem aimed at holding it back. Beijing wants to appear firm in defending its territorial claims, which Chinese people overwhelmingly believe are legitimate.

The angry emotions in China also reflect a thinly veiled animosity toward Japan that is rooted in Japan’s brutal military occupation during World War II.

China’s anti-Japan sentiment from the war has surfaced repeatedly despite the deep economic relations that have developed between the two countries. Revisions to Japanese textbooks that played down or ignored Japan’s wartime atrocities in China and other colonized Asian countries have always been a sore point. Relations were aggravated, too, by repeated visits to a Japanese war shrine by Junichiro Koizumi, a former prime minister, during his 2001-6 term.