Retired Gen. Wesley Clark, a former Democratic presidential candidate now supporting Barack Obama, said Sunday John McCain's military service does not automatically qualify him to be commander in chief. Underscoring during a national television appearance a position he has been expressing for several weeks, Clark said performing heroic military service is not a substitute for gaining command experience. "In the matters of national security policy making, it's a matter of understanding risk," he said on CBS' "Face the Nation." "It's a matter of gauging your opponents, and it's a matter of being held accountable. John McCain's never done any of that in his official positions. I certainly honor his service as a prisoner of war. He was a hero to me and to hundreds of thousands and millions of others in the armed forces, as a prisoner of war. "He has been a voice on the Senate Armed Services Committee, and he has traveled all over the world, but he hasn't held executive responsibility," Clark said. "That large squadron in the Navy that he commanded - that wasn't a wartime squadron." Moderator Bob Schieffer, who raised the issue by citing similar remarks Clark has made previously, noted that Obama hadn't had those experiences nor had he ridden in a fighter plane and been shot down. "Well, I don't think riding in a fighter plane and getting shot down is a qualification to be president," Clark replied.