Traditionally:
If a USN ship was cruising tandem with a Japan MSDF ship and the latter came under attack, the US ship was obligated to come to it’s defense.
But if instead the US ship was attacked, legally speaking the Japanese ship —WITHIN SIGHT of the fighting— was obligated to TAKE NO ACTION.
Ehmmm…..there were objections to this in Japan, but it was touchy, and now they are re-examining all of this.
More and more they are looking realistically at the Chinese threat to the whole region and more understand that in a conflict scenario they might have to act to defend ANOTHER in order to defend themselves.
10 years ago I would have said this “another” would be the USA, however now I think that now may well be a country other than the USA.
Also the prompt willingness of Japan to go their own 100% domestic development route with their stealth fighter prototype indicates to me they have caught a strong whiff of US stagnation and are taking seriously their own defense in an era with a qualitatively different type of USA, i.e. a financially and militarily much weaker USA.
Abe is trying to act like he is walking this back without walking this back. He probably thinks he has to thread the needle because of the LDP loss in the Shiga Prefecture gubernatorial election, though that was a bit like similar elections here, with the LDP getting 44%, opposition getting 46%, and third party getting 10%: the LDP would have won in a straight two-man race.