Updated

Sen. John Kerry (search) accused President Bush on Thursday of relying on front groups to challenge his record of valor in Vietnam, asserting, "He wants them to do his dirty work."

Fighting back, Kerry said if Bush wants to "have a debate about our service in Vietnam, here is my answer: 'Bring it on."' Bush served stateside in the Texas Air National Guard during the war.

"Thirty years ago, official Navy reports documented my service in Vietnam and awarded me the Silver Star, the Bronze Star and three Purple Hearts," Kerry said in remarks to a firefighters convention.

"Thirty years ago, this was the plain truth. It still is. And I still carry the shrapnel in my leg from a wound in Vietnam."

Kerry received five medals for his service in Vietnam a generation ago, but his record has come under campaign challenge in television commercials aired by "Swift Boat Veterans for Truth," funded by supporters of the president.

Bush and the White House have refused to condemn the ads, despite calls to do so — from Sen. John McCain (search), R-Ariz., a former Vietnam prisoner of war, as well as from Democrats.

Senior Democrats, including some inside the presidential campaign, have urged Kerry to respond forcefully to the criticism, fearing that if left unanswered, it could undermine his claim as a war-tested veteran ready to assume command in an era of terrorism.

In a rapid response to the Democrat's speech, Bush campaign spokesman Steve Schmidt said the charge "leveled by Senator Kerry is absolutely and completely false."

"The Bush campaign has never and will never question John Kerry's service in Vietnam. The president has referred to John Kerry's service as noble service," the Bush spokesman said.

At the same time, neither the president nor any of his spokesmen has condemned the ad.

In addition to Kerry's speech before an audience of firefighters, his campaign released a new 30-second campaign commercial that features a former Green Beret saying the then-young Navy lieutenant saved his life under fire.

Recalling when his boat came under attack more than 30 years ago, Jim Rassmann says, "It blew me off the boat. All those Viet Cong were shooting at me. I expected I'd be shot. When he pulled me out of the river, he risked his life to save mine."

Aides said the commercial would air in Ohio, West Virginia and Wisconsin, three battleground states where the original anti-Kerry ad ran. The decision to advertise even in a limited fashion marked a change in course for the campaign, which had hoped to remain off the air for August to conserve cash for the fall campaign.

Kerry's remarks came as The Washington Post reported that records concerning a Vietnam veteran who claims in the anti-Kerry ad that the Massachusetts senator lied about being under fire was under constant attack himself during the same skirmish.

The newly obtained records of Larry Thurlow's medal citation show that he, like Kerry, won a Bronze Star in the engagement and that Thurlow's citation says he also was under attack, the Post reported.

In his speech, Kerry employed a wartime metaphor.

"More than 30 years ago I learned an important lesson. When you're under attack the best thing to do is turn your boat into the attack. That's what I intend to do today."

Speaking of the organization airing the ads that challenge his war record, Kerry said, "Of course, this group isn't interested in the truth and they're not telling the truth. ...

"But here's what you really need to know about them. They're funded by hundreds of thousands of dollars from a Republican contributor out of Texas. They're a front for the Bush campaign. And the fact that the President won't denounce what they're up to tells you everything you need to know. He wants them to do his dirty work."

Kerry said, "Of course, the president keeps telling people he would never question my service to our country. Instead, he watches as a Republican-funded attack group does just that."

Kerry's comments drew boisterous cheers from members of the union that had endorsed him last year at a time his candidacy was struggling.

Rassmann, too, played a pivotal role in Kerry's campaign turnaround last winter. With the kickoff Iowa caucuses days away, the former Green Beret contacted the Massachusetts senator's aides and volunteered to appear with him to talk about Vietnam.

Rassmann has since become the best known member of a group of veterans that Kerry calls his "band of brothers" — a stress on military service designed to erode the traditional Republican campaign advantage on national security issues.

Thurlow, also like Kerry, commanded a Navy swift boat during Vietnam. He swore in an affidavit last month that Kerry was "not under fire" when he rescued Rassmann from the Bay Hap River.

Thurlow's records, obtained by the Post under the Freedom of Information Act, include references to "enemy small arms and automatic weapons fire" directed at all five boats in the flotilla that day. In his Bronze Star citation, Thurlow is praised for helping a damaged swift boat "despite enemy bullets flying about him."

Thurlow, a registered Republican, said he was angry with Kerry for anti-war activities after his return to the United States, especially his claim that U.S. troops committed war crimes with the knowledge of their officers up the chain of command.

Thurlow told the Post that he got the award for helping to rescue a boat that was mined. He said he believed his own award would be fraudulent if it was based on coming under enemy fire.

He speculated that Kerry could have been the source of at least some of the language used in the citation.

Members of Kerry's crew have said Kerry is telling the truth. Rassmann said he has vivid memories of enemies firing at him from both banks.