President Bush said Wednesday that Sen. John Kerry's (search) views on national security are so misguided that the Democrat would be unable to defeat terrorism.

"The next commander in chief must lead us to victory in this war and you cannot win a war when you don't believe you're fighting one," Bush told hundreds of supporters in a northern Iowa farming community.

"My opponent also misunderstands our battle against insurgents and terrorists in Iraq, calling Iraq 'a diversion from the war on terror,"' Bush added.

Bush criticized a recent comment by Kerry that the events of Sept. 11 hadn't changed him much and a comment by Kerry's top foreign policy adviser that the nation is not in a war on terror in a literal sense.

The Kerry campaign is guilty of "a fundamental misunderstanding of the war we face and that is very dangerous thinking," the president said.

Kerry said the case of terrorist Abu Musab al-Zarqawi (search), who is engaging in beheadings of Americans in Iraq and has pledged his allegiance to Usama bin Laden (search), "shows how wrong" Kerry's thinking is.

"If Zarqawi and his associates were not busy fighting American forces, does Sen. Kerry think he would be leading a productive and useful life?" asked Bush. "Of course not. And that is why Iraq is no diversion."

Bush was campaigning in three Midwest states that all went against him four years ago and where polls show him in a close race with Kerry. He also was campaigning in Minnesota and Wisconsin.