An adviser to former President Richard Nixon said military leaders in Iraq are repeating a mistake made in Vietnam by not applying the full force of the military to win the war. "Every asset of the nation must be applied to the conflict to bring about a quick and successful outcome, or don't do it," Alexander Haig said. "We're in the midst of another struggle where it appears to me we haven't learned very much." The comments by Haig, also a Secretary of State under President Ronald Reagan in the 1980s, were made Saturday at a conference examining the Vietnam war and the American presidency. But talk at the event that brought together advisers from the administrations of presidents Nixon, Lyndon B. Johnson, and John F. Kennedy turned to Iraq where the panelists saw parallels with Vietnam. Former Nixon Secretary of State Henry Kissinger made a rare appearance at the conference. He was greeted outside by about 25 protesters who chanted "Kissinger should go to jail, no bail." Kissinger spoke about the war in Iraq, saying he supported the invasion. "We have a jihadist radical situation," he said. "If the US fails in Iraq, then the consequences will be that it motivates more to move toward the radical side." But he was more reluctant to discuss Vietnam, dodging a question submitted by the audience about whether he wanted to apologize for policies that led to so many deaths in Vietnam. "This is not the occasion," Kissinger said. "We have to start from the assumption that serious people were making serious decisions. So that's the sort of question that's highly inappropriate." He added that the Vietnam War "has fundamentally affected my life in the sense that the Nixon debate doesn't ever seem to end and for many I am the surviving symbol of the Nixon administration." Former Johnson adviser Jack Valenti said that the lessons of Vietnam have been "forgotten or ignored" in Iraq. "No president can win a war when public support for that war begins to decline and evaporate," he said. Valenti, former head of the Motion Picture Association, added there was no such thing as a good war, saying "all wars are inhumane, brutal, callous and full of depravity."