BEIJING - The action in the skies over the East China Sea started simply enough.
Last week, the Chinese government sent a civilian surveillance plane, a twin propeller aircraft, to fly near the uninhabited islands at the heart of a growing feud between China and Japan. Tokyo, in response, ordered F-15 fighter jets to take a look at what it considered Chinese meddling. The Chinese then sent their own fighters.
It was the first time that supersonic Chinese and Japanese military fighters were in the air together since the dispute over the islands erupted last year, significantly increasing the risk of a mistake that could lead to armed conflict at a time when both countries, despite their mutual economic interests, are going through a period of heightened nationalism that recalls their longstanding regional rivalry.
The escalation comes amid a blast of belligerent discourse in China and as the Obama administration delayed a visit to Washington requested by Shinzo Abe, the new prime minister of Japan, the United States' main ally in Asia. After the rebuff, Abe announced that he would embark on a tour of Southeast Asia intended to counter China's influence in the region. On Friday, however, he cut short the trip to return to Tokyo to deal with the hostage crisis in Algeria.
What began as a seemingly minor dispute is quickly turning into a gathering storm, military analysts and Western diplomatic officials warn, as each country appears determined to force the other to give ground.
"What is really driving things is raw nationalism and fragmented political systems, both on the Japanese and even more so the Chinese sides, that is preventing smart people from making rational decisions," said Thomas Berger, an associate professor of international relations at Boston University.
The backdrop for the dispute over the islands, which the Chinese call the Diaoyu and the Japanese refer to as the Senkaku, is the changing military and economic dynamic in the region. Though Japan is far richer than China on a per-person basis, its economy has been stagnant for years. China's fast-growing military still lags behind the Japanese Self-Defense Forces in sophistication of weaponry and training, but Japan's edge is diminishing, according to Western defense analysts.