Democratic presidential candidate John Kerry (search) said Thursday President Bush has undermined American leadership by choosing force in Iraq before exhausting diplomacy and vowed that if elected president, he would "never let ideology trump the truth."

"Everyone outside the administration seems to understand that we are in deep trouble in Iraq," Kerry said as he began an 11-day campaign focus on national security.

Kerry said the Bush administration has disregarded the advice of professional military officers and ended the careers of those who gave honest assessments that countered the administration view.

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"That is not the way to make the most solemn decisions of war and peace," Kerry said. "As president, I will listen to and respect the views of our experienced military leaders and never let ideology trump the truth."

Although Kerry's advisers promoted the speech as a major policy address, the Democrat did not stake new ground as he outlined positions he has taken on the campaign trail in recent months. He said he will provide details in the coming days.

The speech was designed to show that Kerry, a decorated Vietnam War veteran, would be strong in combatting terrorism and in his command of the military while confidence in Bush's leadership has softened amid increasing violence in Iraq. The Bush campaign portrayed the speech as disingenuous political grandstanding.

"John Kerry's approach to the war on terror has been filled with indecision and vacillation," said Bush campaign spokesman Steve Schmidt. "He has consistently played politics with the war in Iraq."

Bush sought to rally international support for the transfer of power in Iraq Monday night, and on Tuesday he spoke to French President Jacques Chirac (search) by telephone in advance of the upcoming G-8 summit. Kerry encouraged Bush to seek more support and more international troops during that session.

Kerry said if elected, his top security goal would be to prevent terrorists from obtaining weapons of mass destruction. And he said the United States needs help from other countries because terrorists are working across the globe.

He laid out four principles that would guide his national security policy:

— New alliances with foreign countries;

— An updated military to meet terrorist threats;

— The use of diplomacy, intelligence, economic power and "the appeal of our values and ideas" to keep the country safe;

— Freedom from dependence on oil from the Middle East.

"These four imperatives are a response to an inescapable reality: War has changed; the enemy is different — and we must think and act anew," Kerry said.

If elected, he said he would send a message to the armed forces on his first day in office, promising to make them the "best-led, best-equipped and most respected fighting force in the world."

"You will never be sent into harm's way without enough troops for the task, or asked to fight a war without a plan to win the peace," Kerry said. "And you will never be given assignments which have not been clearly defined and for which you are not professionally trained."

Kerry also had a message for those who may be planning an attack against the United States as the country is facing an election: It is united in determination to destroy terrorist threats.

National security was Bush's strength early in the presidential race, but insurgent uprisings in Iraq and the prisoner abuse scandal have increased skepticism about Bush's handling of the war. Kerry hopes to convince Americans that he would be a better world leader even though military leadership has traditionally been seen as a Republican forte.

"At stake is a vision of an America truly stronger and truly respected in the world," Kerry said. "This is not a partisan cause. Patriotism doesn't belong to any one party or president."

Schmidt dismissed Kerry's statement that the war is not a partisan cause, citing recent criticism of Bush's Iraq policies from House Minority Leader Nancy Pelosi (search), D-Calif.; Sen. Edward Kennedy (search), D-Mass., and former Vice President Al Gore (search). "His claims to the contrary are belied by the facts," Schmidt said.

Kerry's national security tour extends through Memorial Day and will end on the 60th anniversary of D-Day on June 6. He will make two more major speeches in West Palm Beach, Fla., on Tuesday, and Independence, Mo., on June 3, but also take his case to the battleground states of Wisconsin, Minnesota and Ohio.