This link is worth a read - and is accurate
Though I don't pretend to be an expert in philosophical international evolution of western society, I'm presuming the reason for the present state of our armed forces is straight forward.
You are still thinking on the fact that your a sovereign country and your armed forces should be able to stand on their own. I presume the long term trend, though not official is leading towards an integrated defense force.
Another words any enemy who is big enough to worry you with what you have, will not be confronted alone.