Perhaps to replace some American troops Trump will pull out as part of the NK agreement.
Japanese have longed talked about continued use of American bases should we abandon them.
On the other hand, it could be an ongoing effort by US to get Japan to send actual fighters to conflict areas rather than just monetary and logistical support.
But I don't see any concerns over Japan being agrtessive in East Asia. The people would not stand for it again…no god emperor.