I spent 3 years in Japan with the US Navy. Although the various Japanese self defense forces (Maritime Self Defense Force, Air Self Defense Force, etc, etc...) are very capable of defending themselves, it is my opinion that they are indeed becoming extremely dependent on the U.S.
They have state of the art equipment (most of which was bought from us), motivated personnel and a strong sense of pride in their work. All these things add up to an effective fighting force. However, the government spends percious little on Research and Development relying heavily on the U.S. and Britain for it's military upgrades. This is very strange since the Japanese excel at improving existing technology. Also, they drag in monetary commitment spending less than 2% of their GDP on defense.
I disagree diceke, in that America will not be permenant allies.
Japan provides an excellent forward deployed base for operations in Asia and we provide and excellent deterrant force against North Korea and China. it's a perfect symbyotic relationship and as long as NK remains a threat and China a reputable military power, this will not change.
The relationship is changing however, Japan is becoming more involved with it's own defense, first with the forming of the Ministry of Defense early this year. Second, as part of the deal that would allow the U.S. to bring the nuclear aircraft carrier USS GEORGE WASHINGTON to replace the aging non nuclear carrier USS KITTY HAWK, we were made to relocate 10,000 Marines from
Okinawa to Guam. This shows that Japan is trying to take a stronger stance in their relationship with the U.S. perhaps trying to make the full transition from silent partner to active participant in it's national defense.
Wow, that was a lot longer than I intended. My point is that as the world situation develops, I do believe that Japan will be granted full military development and purchasing capabilities. I do believe than in the next 10 years, a pre-emptive strike may be needed against NK or possibly even China. I think the restraints placed on Japan after WWII are antiquated and no longer relative to the modern world. Only time will tell though.