As I am not an American I cannot comment on the greater part of John Knight's June 20 letter, "Be careful about wishing the U.S. away," but as I am ex-U.K./NATO military, I can comment on the latter part.
It is easy to understand the feelings of many Japanese — especially in Okinawa — that the United States continues to "occupy" Japan and that many would wish them to depart. But if the U.S. were to leave Japan alone to defend itself — which is so unlikely as to be discounted! — the Japanese people would perforce have to discard their antiwar peacefulness and not only upgrade their military but also amend/rewrite their Constitution, especially Article 9.
Does anyone really believe they would do that? I think not. So, the U.S. military will remain on their Far East "aircraft carrier" ad infinitum, despite the unlikely event of any attack on Japan and despite the discontented voices of the people.
I have long held the belief that Japan should have a new constitution "for the people, of the people and by the people" with absolutely no outside interference or influence. It should discard the current "U.S.-imposed" one and then let the people decide in a referendum whether they want to live and feel "secure" under the American "umbrella" or not.