1000 troops, wow.
Japan is not playing any games.
For what? Beyond posturing, I don't understand what is happening here. What's the purpose? To scare off the other nation's fishing boats? Zroc is working hard up there to demonstrate that these islands have some sort of defensive relevance, but they really don't. They're indefensible against anything but, quite literally, fishing boats. You could build an air strip, sure, and use it a re-fueling station, but the moment any sort of unrestrained conflict breaks out the opponent is going to bomb that to shit.
Building an airstrip or a couple platforms doesn't mean they'll hold up to a real offensive. Where is the perimeter for your AA? Where is the cover? Where is the proximal major island that can house troops & ships to deploy as an effective naval shield? Nowhere. These things are at least 330km+ from both China and Japan's nearest controlled land which could offer that sort of functional, ancillary support for the outpost. That's close enough to bomb, easy...not close enough to so easily defend.
I don't see any military application they could have beyond housing an observation outpost with just a few small structures and a few troops: a target unworthy of the resources of any sort of serious dedicated air raid.
The claim to these islands isn't even about the potential oil reserves in their supposed vicinity. This is pure dick measuring in the escalating and ongoing the South China Sea saga. They are not, nor have they ever been, a significant military preoccupation.