In the movie "Shin-Godzilla" it's Nichibei Ampo (Japan-U.S. Security Arrangements) which is the legal basis for request of support to the American army, so I'd like to talk about it as trivia.
Right from the start, why American army stay in Japan now ? I believe it's a little known fact that it's the marine force stationed in Japan which is good at landing operation.
So if you ask the question to specialists of Japan-U.S. relations, I guess other half answer it's to invade Japan when Japan spur militarism again, and another half answer it's for Japanese but not
to fight with invader to Japan, but to invade Korean Peninsula and stop communists at there.
(Therefore I think Donald Trump is fuckin liar but clever businessman because he may understand because of the end of cold war, demand of US military in Japan has relatively decreased for America so he might think he can squeeze more money.)
I don't mean to say American army has no deterrent power, but it is said that Japan-U.S. Security Arrangements has a fatal loophole so I believe American won't help Japanese when china invade Japan despite of claim of Trump.
In facts if you see the articles of Japan-U.S. Security Arrangements, you'll find there is no words "use of force" or "defense obligation" (I think this fuzziness is intentional because article 5 of North
Atlantic Treaty definitely says "forthwith" the parties do necessary "including the use of armed force"!)
In article 9 it declares that the parties "would act to meet the common danger in accordance with its constitutional provisions and processes". So this treaty only guarantee America submit the action to
the Congress for approval, no more and no less. Needless to say if the American Congress were to vote down, Japan would have no future...
It's a sad but true democracies do war only when people are fascinated with sense of justice and it has a actual advantage for politicians. Iraq has both of them, but Senkaku islands has neither of them.
Is Japan a important alliance partner for America ? or just a client country ? I believe many of American people might think "WTF? why we must die for the far east island where no one live?" and many of American politicians might be reluctant to alienate China whose GDP overtake Japanese now.
U.S.-Japan alliance also has so many demerits for Japan. At okinawa islands helicopters make a flights over the residential area everyday (but they keep out from the area where American live because it's a loud and dangerous !). And when marine rape girls Japanese can't bring them into custody if they escape to the military base because it has extraterritorial right !
(Recently in some cases American army turn suspects over to the Japanese police before indictment by "sympathetic consideration", but it's also true American governments keep a negative attitude to update the U.S-Japan Status of Forces Agreement)
Though for the moment many of Japanese have a favorable view of America and not really want militarism. But if Japanese were to learn U.S.-Japan alliance is just a fictitious bill and loyalty to America for 70 years is completely meaningless, I can't deny the possibility that a radical right regime would be born in Japan which insist on nuclear armament and independence from America...
In the next last chapter, I'd like to talk about relation between the movie and atomic weapon.