budget allocation for sympathy

Japan and U.S. Agree on Marine Transfer

Japan and the United States have reached an agreement in which Tokyo
will pay 59 percent of the cost of transferring 8,000 U.S. Marines from
Okinawa to the American territory of Guam, the chief of the Japanese
Defense Agency announced on Monday.

Where does the money come from?
Do we really have to pay for it?
We should spend the money for falling birthrate and for aging society.