This article describes how some Chinese military vessels docked in Australia without being pre-announced to the public.
It's getting attention because these are Chinese warships and it's close to the timing of the Tiananmen Square massacre. if it were another country would it go unnoticed
I'm really after an understanding of the general political conventions and examples in prior history, so I can understand if the way it is generally being reported is reasonable or unreasonable.
It does not have to have media attention to be what I would consider publically announced. It could be in a registry somewhere that is accessible to interested parties.