Earlier this week Kyodo News dropped a bombshell (pun intended) by introducing the contents of declassified U.S. documents that the U.S. government turned down a request in June 1978 for its military based in Japan to use its firing and bombing ranges in the Senkaku Islands.
The reason given in the story, reprinted on April 5 in The Japan Times ("U.S. ceased using Senkaku islets as firing range in 1978 to avoid riling China"), is that the U.S. government feared “it could become embroiled in a Sino-Japanese territorial dispute.”
Although the fact that the U.S. military has not used the ranges since that time is commonly known, the reason for it has been one of speculation without the supporting documents. Thus, the importance of the Kyodo reporting.