Both India and Japan have evinced interest in deploying defences against ballistic missiles because of the threat they pose. Significantly, both have shifted their stance on US Ballistic Missile Defence (BMD), from previous opposition to active support. Notwithstanding certain basic differences between India and Japan on the nature and degree of interest and participation at present, shared interests offer an opportunity for them to cooperate with each other on the BMD issue to further consolidate the 'strategic partnership' understanding they have evolved. Since Japan is already actively collaborating with the United States in not only deploying BMDs but also co-developing certain critical components, and India actively weighing various options, including cooperation with the United States, in this field, it may become imperative for India and Japan to cooperate once India takes a firm decision on BMD deployment. Apart from common concerns about proliferation of weapons of mass destruction and missiles, in particular the clandestine deals between North Korea and Pakistan, the strategic relations between the two countries have so far been focused on the maritime cooperation. Joint work on missile defence could become a new dimension of bilateral relationship and help co-development of advanced technologies.