China is doing exactly what you say with islands in the Pacific that they promised not to militarize and then moved in military bases. There balance of military power hasn't tipped at all, the western countries just stopped thinking it was okay to establish permanent settlements in other people's countries and then use that to claim we owned it. We still create best permanent military bases when we want to. If Britain or the US wanted we could destroy the Chinese Navy and Air Force without blinking. It's only when you get to ground forces that you see any kind of advantage in the Chinese military, because like the USSR in WW2 there are always more bodies.