Collecting, restoring and researching electronic marvels of a past era and of a country that was a domminent world leader, I find it hard to conceive how quickly it was taken away.
The text from a PBS documentry will be familiar some and an eye opener to others.

http://www.zoklet.net/totse/en/politics/economic_documents/pbsjapan.html

...all taken from Pat Choate's book "Agents of Influence" - bottom line was concessions to the Japanese in dealing with cold-war desires of the US.

The book is a good read - a large part is on Google books.

Cheers,

If you are interested in this general topic (Postwar U.S.-Japan relations), be sure
to have a look at 'Legacy of Ashes', by Tim Weiner.