Rumors are fluttering around that the United States and Japan had an agreement during the Cold War which allowed nuke armed US ships to occupy Japanese waters and make port calls in an effort to attain strategic advantage over Russia. A foreign ministry official commented on the issue stating, “Such speculation has gone on for decades, but the government of Japan has said there is no such secret agreement.” A paper called the Mainichi Shimbun national daily printed a document which allegedly illustrates the agreement between the United States and Japan.
Historians agree that such an agreement between the US and Japan would be plausible because of the United States vast influence on Japan. Since our attack with the atomic bomb, Japan has been forced to cooperate with our requests. Therefore, from a Japanese standpoint, such an agreement is in no way inconceivable.
From an American standpoint the agreement is likely as well. The US has a history of networking and using ties in order to gain strategic military positioning.
So why is this such a big deal? In 1968 Japan developed a policy which stipulated that they would not build, house, or allow any nuclear weapons in their territories. If they were letting US vessels with nukes into their ports and waters, they would be violating this policy to which they had proclaimed allegiance.
For the international community to see Japan violating this agreement would tarnish their reputation. That is why Japan is so adamantly denying that they ever allowed US ships into their ports.
I honestly cannot say whether or not it has happened. There is a document which was published in the paper which would suggest that this agreement did take place. However it is not a foolproof case.
