(CNN) -- A group of Vietnam veterans opposed to John Kerry's presidential campaign demanded Tuesday that he remove a photograph that appears in one of his television advertisements.
In Tuesday's "cease and desist" letter, Swift Boat Veterans for Truth called on Kerry's campaign to stop what it said was the unauthorized use of the images of some of them in a 60-second biographical spot titled "Lifetime." The ad began running nationwide in early May.
The U.S. Navy photo in question depicts 20 officers, including Kerry, and was taken January 22, 1969, on the island of An Thoi in Vietnam. The ad shows only a portion of the picture -- not all of the men are visible -- and is displayed for two seconds.
But even the men who are not in the ad have a right to demand the picture not be used, said Alvin A. Horne, a Houston attorney who served on a swift boat in Vietnam in 1969-1970. He is giving legal advice to the group. Eleven of the 20 men in the picture oppose their images being used in the campaign ad, he said.
"The use of the 11 images in this political campaign wrongfully and incorrectly suggests their present endorsement of his candidacy for president of the United States of America," said the letter, which Horne wrote.
The group describes itself as a non-partisan, public advocacy organization and is led by retired Rear Adm. Roy Hoffmann.
Formed four weeks ago, it comprises more than 220 veterans from the naval units in which Kerry served in 1968-69. Kerry led a pair of high-speed, 50-foot crafts, known as swift boats, that patrolled the Mekong Delta to disrupt Vietcong supply lines.
During a four-month period, Kerry, then a 25-year-old lieutenant, was wounded three times, earning three Purple Hearts. He was awarded a Silver Star and a Bronze Star for his performance under fire.
After his discharge in 1970, Kerry became an outspoken critic of U.S. policy and a leader of Vietnam Veterans Against the War, testifying in April 1971 against the conflict before the Senate Armed Services Committee.
Kerry's comments at that time that U.S. soldiers had committed "atrocities" have angered the group.
The letter charges that Kerry "tarred the entire serving military in Vietnam with his black brush." In April, Kerry expressed regret for his choice of words in 1971.
He characterized some of his comments as "over the top" and said he never intended to cast a negative light on the men with whom he served.
The letter, sent to campaign general counsel Marc Elias, says the campaign neither sought nor obtained consent from the fellow veterans to use their images in the ad. It asked them to stop using the picture within 10 days.
"Suing is a possibility," said Horne, who would not divulge whether he has any political affiliation. "That's my business. This is not about me and my politics. I didn't have an 'R' stamped on my dog tags."
A Kerry spokesman dismissed the group's claim, noting the Swift Boat Veterans used an enlarged version of the same photo at a news conference announcing the anti-Kerry group's formation in early May.
"Somehow they didn't call to ask if they could use John Kerry's image," Michael Meehan said. "When it was useful for their politics they show a big blowup."
