Washington, June 28: Besides losing his credibility, US President George W Bush's new doctrine of preventive wars will be in jeopardy if he does not manage to find any Weapons of Mass Destruction in Iraq, a US historian has said. "President Bush will lose his credibility and he will not be able to engage in preventive wars, his new doctrine which replaces the old doctrine of containment and deterence, if he wants to do so, against Iraq or North Korea, historian Arthur Schlesinger, who served in the Kennedy administration, says in an article in the Washington Post today. Even if a cache of WMD is found somewhere in Iraq, he says, it will not be sufficient to rescue the president. The bottom line question is, Why were the WMD not employed? Ehen Saddam Hussein was fighting for his regime, his power and his life, why in the world did he not use the WMD against the us invasion.