Q&A: John Kerry's Vietnam service

Kerry's medals in Vietnam have been the subject of attacks

Democratic presidential candidate John Kerry's campaign has highlighted his service in Vietnam, showcasing veterans who served with him. Their testimonies to his heroism and leadership have been credited with helping him win his party's nomination.

But now a group of veterans is running adverts questioning events that led to John Kerry's war medals and highlighting anti-war statements he made after his return to the US.

What do the anti-Kerry ads claim?

John Kerry commanded a craft called a swift boat in Vietnam. A group calling itself Swift Boat Veterans for Truth has accused him of lying to get one of his medals for bravery and two of his three Purple Hearts - medals awarded for being wounded in the line of duty.

In an advertisement, Van O'Dell says that he was on a swift boat yards away from Mr Kerry during the incident in which he was awarded the Bronze Star for bravery.

He said there was no enemy fire during the incident. Another member of the group, Larry Thurlow said: "Kerry fled while we stayed to fight."

Louis Letson - a doctor who says he treated Mr Kerry in Vietnam - claims that the candidate did not deserve his first Purple Heart. Mr Letson says the wound was self-inflicted.

Political ad watchdog FactCheck.org says that this contention is based on disputed hearsay.

There are discrepancies in the record for the second Purple Heart. An explosion threw Mr Kerry into the bulkhead on his swift boat.

Navy records for the award state he had bruises on his arm whereas his citation for the Bronze Star medal for bravery say his arm was bleeding.

How has Mr Kerry responded to the attacks?

The Kerry campaign has responded with advertising of its own

Jim Rassmann - an Army Special Forces lieutenant who credits Mr Kerry with saving his life - has rejected the criticism in counter-advertisements.

Although he is a Republican, Mr Rassmann has been campaigning for Mr Kerry.

He says an explosion blew him off Mr Kerry's boat, and he repeatedly swam to the bottom of the river to avoid enemy fire.

Mr Rassmann says he expected to be killed until Mr Kerry exposed himself to enemy fire in order to pull him to safety.

Who are Swift Boat Veterans for Truth?

The group formed in the spring of 2004 after it became clear that John Kerry would win the Democratic party's presidential nomination.

The group is known as a 527, after the section of the US tax code that governs this type of organisation.

Such groups have been prominent in this election because they can take advantage of a loophole in the campaign finance reforms that were passed after the last election.

The reform's limits on donations do not apply to 527s. Some $260m has been given to such groups during this election cycle, according to PoliticalMoneyline.

Contributions to Democrat-leaning 527s have outpaced contributions to groups sympathetic to the Republican party and George W Bush.

Does Swift Boat Veterans for Truth have ties to President Bush's re-election campaign?

By law, the group cannot directly coordinate its efforts with the Bush campaign, and the Bush campaign has said it has no connection with the ads.

Democrat-leaning groups have attacked Bush's service record

But the Kerry campaign says that the group is a front for the Bush campaign and has called on President Bush to denounce the ads.

Retired Air Force Colonel Ken Cordier, who appeared in one of the group's ads, has served on the Bush campaign's veterans' steering committee. Mr Cordier has since resigned.

Records show that Houston builder Bob Perry gave $100,000 to the group, a majority of its initial funding.

Mr Perry and his wife have given millions to the Republican party, including $6,000 to President Bush's campaigns.

Mr Bush has declined to denounce the ads, despite calls from the fellow Republican and Vietnam veteran John McCain, but he did call for an end to all advertising by 527s, and praised Mr Kerry's military record.

Have 527s been attacking Mr Bush as well as Mr Kerry?

Mr Bush has been the target of attack ads from Democratic-allied 527s, most notably MoveOn.org, which has been running an ad critical of Mr Bush's Vietnam-era service record.

The Bush campaign has charged that the Kerry campaign has contacts with Democratic-leaning 527s because former Kerry campaign manager Jim Jordan works for a pair of 527s.

Both campaigns have accused the other of illegal co-ordination with 527s and filed complaints with election regulators.