No, I do not believe that the United States should send troops to Australia. In reality we are spread thin already. We tend to be the world police. What happens when we need those troops here in the United States. We have troops in places that they have no business being in being killed already we don't need to expand the reach to Australia.
Never mind, we are sending troops to Australia to be a buffer against China. Talk about a story that is not getting much attention. I do not really know what 250 Marines are going to do in Australia, as regards to China. It would be one cool duty station to be deployed to though. There isn't a lot of marines either, which would make the time all that more fun. In all seriousness, it kind of sounds like a waste of resources and the troops should not be sent.
The US sent troops that, together with the Australians, fought Japan and the Japanese colonies during the Second World War but since then, the threats are far lower. The US is a long term ally of Australia, both Anglophone former British colonies, and the US bases in Japan are enough to protect interest in Asia.
I do not believe that the USA should send troops to Australia. I think that there isn't any reason for the United States of America to send troops to Australia. I think that United States shouldn't waste any funds and efforts regarding the subject. It is more important that the USA uses their resources in countries like Afghanistan.
I think the Australia is able to provide their own military and troops for their own purposes, there is no nation that is providing a meaningful threat to Australia that would require the United States to spend resources and manpower providing troops to the nation at the current time in the world.