The turn around that Japan has done since WW2 going from foe to friend has been extreme. A people we once loathed to destroy in revenge after Pearl Harbor and lockup in interent camps, those that were already in our country are know a very strong allie.
I'd have no problem at all if we let them put thier forces back together or even have nukes for that matter.
We already have nuclear weapons in Japan and SK. Maybe We could just let them push the button?
The Japanese like Rice. :)
Japan hold more US debt than China. Japan will never dump it because we defend them. This is what's going on. They hold our debt and we defend them
Proliferation chains
China wanted a bomb because it stopped trusting the Soviet Union.
Then India wanted a bomb because it had bad blood with China.
Then Pakistan wanted a bomb because it had bad blood with India.
Meanwhile, in the Middle East, Israel built nuclear weapons for protection against the Muslim states.
Egypt, Syria, Libya, Iran, and Iraq then decided they needed the security of mutually assured destruction vis-a-vis Israel.
And let's not forget North Korea versus everybody.
Or Taiwan versus China. Or the government of the Philippines versus the insurgents of Mindanao.
You can keep going like this for a long time. The harder you look, the more pairs of (ever-smaller) opposing parties pop into view throughout the world, each a potential Petri dish for mad thinking.
http://encarta.msn.com/column_nukes_tamimhome/Whosgotnukes.html
A nuclear Japan would strengthen both Japan and the United States. That's why China would get upset.