Singapore has no strategic depth anyway, becoming dependent on importing power isn't some extra vunerable vector vs building domestic generation that likely can't be protected long term. Current is Singapore military vs region is like PRC:TW in the 90s... back then TW with US equipment was one of the more potent forces in the region and could stomp far larger/poorer countries with inferior hardware. But advanced equipment can only scale so far vs quantity, and as rest of ASEAN gets wealthier they're going to build out more modern capabilties, at scales that rich but small Singapore won't have the resources to defend against. If anything integration with AU, with military infra (and future US B21s) is probably more secure / geopolitical hedge against other's meddling.