A payment of US$4 million was included in the overall payment of US$320 million to the United States which was agreed to in 1971.
Everything is a secret pact if it's under negotiation. After the United States disclosed the official documents, it was no longer a secret pact.
There was a possibility that the negotiations would come to a deadlock if Japan did not pay.
It was the decision of then Prime Minister Eisaku Sato that Japan would pay (the $4 million) as long as Okinawa would be returned.
