The United States has proposed launching a bilateral dialogue with Japan on possible joint cooperation in the event hostilities erupt between China and Taiwan, Japanese government sources said Monday.

Japan has been put in a difficult position over the proposal, which was made in November at a working-level meeting in Washington to discuss U.S. military realignment in Japan, because the government has not clarified whether Taiwan is covered in the scope of Japanese-U.S. defense guidelines set in 1999.

The bilateral defense guidelines provide for a number of joint activities between the Self-Defense Forces and U.S. armed forces to address emergencies in "areas surrounding Japan."