And also presumably for the Chinese. Who, if the preliminary reports are not to be believed, possibly received a notification that one of their UUVs or subs was damaged. While tensions are high with Taiwan. And there are five(?) international carriers / amphibs conducting manuevers off Japan.
The Navy’s of the worlds job is a whole lot of high tech ‘watching’ of the other Navy’s. So having an official statement seems to make sense. (But I don’t think the GP really meant they shouldn’t say it at all, they just want more details.)