That's part of it. But liberals didn't express the kind of animosity toward the military, at least not as openly, when Bill Clinton was President. They may not have loved the military back then, but to them, it was "their" military.
I think the main reason for their hostility now is they see the military as an extension of President Bush -- its operations are his policies put into action. So they despise the military, because they despise him.
Na, the liberals/MSM have hated America openly for 50 years.
This President is just their latest excuse.
The real question is; what are we going to do about it?