"No. I have always said, across my long, distinguished career of public service, that I would never judge the choices of anyone during the Vietnam War. Not those who chose to burn their draft cards. Not those who chose to flee to Canada. Not those who chose to drop acid and commit public sex acts. Not even those cowardly weasels who chose to serve in the National Guard."
"When I was maneuvering through the Mekong Delta, and the jungle heat was nearly intolerable, some of my comrades in arms would say, 'I hate those cowardly pantywaists who stayed home to serve in the National Guard.' "
Kerry apparently doesn't realize that there are National Guard members serving both here and in Iraq right now. Since these remarks are RECENT, it's obvious he still has a very low opinion of the National Guard.
His accusations against the president therefore stem from his hatred of the National Guard.