So Gen. Clark can't comment on McCain's military past...

but how about someone who lived across the hall from him at the Naval Academy and who was a POW with him? Over at Military.com, Dr. Philip Butler has a very unique perspective that he shares in his article Why I Will Not Vote for John McCain.

Two key quotes -

People often ask if I was a Prisoner of War with John McCain. My answer is always "No - John McCain was a POW with me." The reason is I was there for 8 years and John got there 2 ½ years later, so he was a POW for 5 ½ years. And we have our own seniority system, based on time as a POW.

And

I furthermore believe that having been a POW is no special qualification for being President of the United States. The two jobs are not the same, and POW experience is not, in my opinion, something I would look for in a presidential candidate.