The conflict over the future of Taiwan is usually seen as a triangular struggle among China, which claims the island; Taiwan, where the majority seeks to retain its separation from the mainland; and the United States, which is Taiwan's security guarantor.

That is changing, contends a new study by the National Bureau of Asian Research, a nonpartisan institute in Seattle. It argues that the Taiwan question has become quadrangular, with Japan having become the fourth nation directly engaged in potentially the most explosive clash in Asia.

Japan's entry into the Taiwan issue is yet another indication of Tokyo's emergence as an activist in international relations in Asia after decades of a pacifist and passive stance in what the Japanese call "low posture."

Moreover, the study suggests that East Asia is becoming ever more divided into Chinese and American blocs.

Specifically, it says, "if a military confrontation occurred between the United States and China over Taiwan, U.S. policymakers can rest assured of Japan's support."

President Bush seemed to underscore Japan's new position on Taiwan last month by including warm praise for Taiwan in a speech given in Kyoto, Japan's ancient capital. He applauded Taiwan for having "moved from repression to democracy as it liberalized its economy."

Without naming Generalissimo Chiang Kai-shek, the autocrat who ruled Taiwan from 1949 until his death in 1975, Bush lauded the people of Taiwan for being "free and democratic and prosperous."

The Chinese, who insist that the Taiwan issue is an internal question of no concern to America, were not pleased.

The assessment of Japan-Taiwan relations was written by two Americans, Michael McDevitt and James Auer, both retired naval officers experienced in Asian affairs; two Japanese scholars, Yoshihide Soeya of Keio University and Tetsuo Kotani of Doshisha University; and a scholar in Taiwan, Philip Yang of National Taiwan University.

The study asserts: "Taiwan's quiet initiative to push for a greater level of informal defense contacts with Japan arises in no small part from shared history and democratic values, common strategic constraints and island threat environments, as well as the close relations that both Tokyo and Taipei maintain with the United States."

The shared history is Japan's colonial rule of Taiwan from 1895 to 1945 after the island was ceded by China to Japan following the Sino-Japanese War. Japan's control is generally considered to have been benign, despite several harsh episodes in the beginning.

Strategically, Taiwan sits astride Japan's trade routes through Southeast Asia to the Persian Gulf, a key source of oil, and on through the Suez Canal to markets in Europe. Taiwan is tied to the United States by the Taiwan Relations Act, which requires Washington to help defend Taiwan; Tokyo has a security treaty with America.

In taking this initiative, the authors say, "Taiwan has skillfully seized diplomatic leverage from China, the United States, and Japan, and has used this power to promote an agenda that often tests the bounds of Beijing's tolerance."

President Chen Shui-bian, however, may have overplayed his hand. In local elections earlier this month, his Democratic Progressive Party was thrashed by the Nationalist Party, better known as the Kuomintang or KMT. Chen appears to have made voters worry that he might provoke China into military action against Taiwan.

Sympathetic Japanese attitudes toward Taiwan have risen since the end of the Cold War, the scholar Soeya writes, because of the "deterioration of political and security relations between Japan and China, and Taiwan's steady democratization."

He points to several dialogues between Taiwanese and Japanese legislators and favorable press coverage.

Philip Yang in Taiwan writes that behind the new Japanese attitudes is a postwar generation of politicians who "believe that World War II should no longer haunt Japan's relations with its neighbors but see in China a determined unwillingness to forget the past."

Bashing Japan, he says, has "become part of the political culture in China."

From an American point of view, McDevitt says, the success of democracy in Taiwan "has tipped the political balance in the United States in favor of support for an 'embattled' democracy."

Before, Americans seemed indifferent to Taiwan's plight.

U.S. military leaders, however, are losing patience with Taiwan's refusal to conclude an arms purchase to which Washington agreed four years ago.

Last week, the opposition parties in the national legislature, led by the KMT, voted for the 40th time not to place the arms deal on the agenda so that it could be debated and voted on.

Honolulu-based Richard Halloran is a former New York Times correspondent in Asia. He wrote this for The Advertiser.