I think the Japanese would have to change their constitution to have nukes...or something like that.
They could call it the CLINTON AMENDMENT....because of BJ, they amend their constitution.
In October 2004 a panel of academics, business leaders, and former government officials called for Japan to consider acquiring the ability to launch pre-emptive military strikes. That would move the country away from its purely defensive security policy. The recommendations from the panel will strongly influence the government's official defense review, expected to be issued in December 2004. It is only the third such review since Japan's defeat in World War Two. By far the most controversial proposal recommends that Japan obtain a first-strike capability, allowing it to hit enemy missile bases to prevent an attack. That recommendation, if adopted, would be certain to anger Asian neighbors, especially China and North Korea. The panel, however, came out against Japan having nuclear weapons, saying it must not pose a threat to neighboring countries.
http://www.globalsecurity.org/wmd/world/japan/nuke.htm