In the 1990s and into the new century, increased Japanese sympathy toward Taiwan and antipathy toward mainland China led to a series of moves to improve treatment of Taiwan, including enhanced transportation links, a higher level and frequency of official contacts, posting of a military attaché, and expressions of support for Taiwan's participation in regional and international organizations. Nevertheless, Japan remains firmly wedded to a One China policy that opposes both the use of force by the mainland and a declaration by Taiwan of independence from China. Japan's willingness to cooperate with the United States to defend Taiwan is increasingly in doubt. The sources of Japan's supportive but restrained policy include the decline of traditional ties with Taiwan, the increasing size of the mainland market, and above all a perception of security risks that ultimately diverges sharply from that of Taiwan. Serious cooperation in defense and diplomacy requires shared (or complementary) threats, not just shared adversaries.
