What’s the purpose of being so boisterous about it?
Personally, I think China is already looking for reasons to militarize their economy. Why give them excuses?
Their intelligence would likely know most of what Japan and the west is doing anyway, and it’s doubtful you could hide it much, but this give them propaganda fodder internally.
What ever happened to walk quietly and carry a big stick?
A doubling of an already substantial force is not something that can be hidden.
And there is power in publicly proclaiming it.