Rumsfeld also warned that "moral or intellectual confusion" about which side is right or wrong "can weaken the ability of free societies to persevere."
Borrowing a phrase from the nation's most conservative commentators, Rumsfeld in a new line of attack argued that critics of the Iraq war, like critics of the Cold War before them, were part of a "blame America first" crowd.
"The struggle we are in is too important -- the consequences too severe -- to have the luxury of returning to the 'blame America first' mentality," he told the American Legion. "Can we truly afford to return to the destructive view that America -- not the enemy -- is the real source of the world's troubles?"
Rumsfeld's view of Bush administration critics contrasted with that of Secretary of State Condoleezza Rice, who took a softer tone in a speech to the convention later Tuesday. She appeared to acknowledge that many questions about the Iraq war were fair.
"On the one hand, Americans want desperately to succeed in Iraq. They want to do whatever it takes to achieve victory," Rice said. "But on the other hand, there are unsettling questions. Is success possible? Is it really worth the effort?"
Rice said she believed that the U.S. strategy was working, and that the military must remain in Iraq or risk handing a victory to violent extremists in the Middle East.
"If we abandon the Iraqi people before their government is strong enough to secure the country, then we will show reformers across the region that America cannot be trusted to keep its word," Rice said. "We will embolden extremist enemies of moderation and of democratic reform."
In recent speeches, Bush has acknowledged public concern about the war, saying last week that the conflict was "straining the psyche of our country" and that he would never question the patriotism of those who disagreed with him.
However, Bush too has drawn parallels between his Iraq policies and World War II. Before the U.S.-led invasion, he said: "In the 20th century, some chose to appease murderous dictators whose threats were allowed to grow into genocide and global war. In this century, when evil men plot chemical, biological and nuclear terror, a policy of appeasement could bring destruction of a kind never before seen on this Earth."
Rumsfeld's speech drew sharp complaints from Democrats, including Sen. Edward M. Kennedy of Massachusetts, whose father, Joseph P. Kennedy, was criticized by Rumsfeld in a speech Monday.
