"Is Australia and the USA really allied?"
Yes they are. Aussie fly the F-111, and that's all the proof anybody needs.
The two articles are not related.
1. Rimsfiels is worried about the buildup of Chinese conventional forces.
2. China has more than enough nuclear weapons capability at present.
3. Australia is considering exporting uranium to China. China is considering converting to nuclear power as a way to ensure China's energy needs to drive an accelerated economy into the future.
And just so that everybody is clear, Aussie's do stick a Emu feather in their cap, but they don't call it macaroni.