Japan won't consider developing a nuclear arsenal if the United States adopts a "no first use" policy for such weapons, according to new report by the Ploughshares-funded Union of Concerned Scientists [2], titled "Japan and America's Nuclear Posture." [3]
Some conservatives in the U.S. have suggested that such a change in policy would prompt Japan to consider developing its own atomic weapons.
Links
[1] https://ploughshares.org/file/1633
[2] http://www.ucsusa.org/
[3] http://www.ucsusa.org/assets/documents/nwgs/japan-american-nuclear-posture.pdf
[4] http://www.ucsusa.org/news/experts/gregory-kulacki.html
[5] http://search.japantimes.co.jp/cgi-bin/nn20100325a4.html