LONDON — In terms of life-or-death significance, the most sensational disclosure Prince Harry makes in his 570-page memoir hitting bookstores on Tuesday is that he kept a body count of Taliban fighters he killed while piloting a helicopter in Afghanistan in 2012 as a member of the army.

Titled “Spare,” the book was supposed to be under wraps, but booksellers in Spain sold a Spanish-language edition prematurely, and the British papers are salivating over the inside stories that Harry is spilling about royal family infighting.

Unlike ground troops who generally have no idea how many of the enemy they killed, Harry could add up the numbers by checking the video camera in the nose of his Apache helicopter after he got back to Camp Bastion, the former British base in Afghanistan’s Helmand Province. His reference to the 25 he claims to have killed conjured memories of the Vietnam War, where the American command regularly published estimates of enemy dead. The Americans often boasted of “the kill ratio” — 10 enemy dead for one American.

Like soldiers everywhere, Harry showed no signs of guilt or remorse over killing the enemy. “I didn’t think of those 25 as people,” he writes. “You can’t kill people if you see them as people.” Rather, they were “chess pieces removed from the board, bad guys eliminated before they could kill good guys.”

That may be understandable in the heat of combat, but Harry may have made a mistake in writing about it so openly. One former royal marine, Ben McBean, has publicly advised him: “You need to shut up.”

Quoted by the British press, Mr. McBean, who lost an arm and a leg blown off in an explosion in Afghanistan, took to social media to offer his criticism. Harry’s frankness, he said, “makes you wonder about the people he’s hanging around with.”

The real concern is that the Taliban, now in total control of Afghanistan since President Biden threw in the towel in August 2021 and withdrew American troops, will seek revenge on Harry. Mr. McBean warned, “If the Taliban can’t get access to Harry, they might think about who they can target in the UK.” He said there is “no positive to it coming out.”

The Taliban, however, may take a broader view. A spokesman, Bilai Karimi, said “the issue is not unique to Harry.” Rather, he said, “the forces of all the occupying countries have committed similar crimes in our country.” Western countries, he said, while claiming “to be supporters of human rights … actually commit this kind of crime.”

Harry’s war record, though, was always a matter of concern to the Brits, who knew the Taliban would love to find and kill him if given the slightest opportunity. After compiling a mediocre record as a university student in Oxford, Harry wound up at the historic British military academy at Sandhurst, was commissioned as an army officer, and served two tours in Afghanistan.

He was sent home following the first tour after an Australian newspaper identified him in Afghanistan, giving hints to the Taliban as to his possible whereabouts. The tabloid Daily Mirror said a Taliban commander had planned to get him during his second tour.

Harry, who served 10 years in the army, was discharged as a captain before assuming the royal duties that had him tangling incessantly with big brother William, the heir to the throne. As next in line, Harry was “the Spare” — hence the title of his book. William’s children now rank ahead of him in order of inheritance, making Harry the fifth in line.

Harry by all accounts had an excellent military record, but his superior officers are horrified by the frankness of his public body count. “All the good work Prince Harry did on behalf of the armed forces has been undermined by his comments,” a former commander of the Brits in Afghanistan, Colonel Richard Kemp, said. “Not only has he gone too far in talking about this in terms of himself but it may have repercussions for others.”

His comments, Colonel Kemp said, “may affect the security of his former comrades on foreign operations.”

Correction: Prince Harry served in the army. An incorrect service branch was referenced in an earlier version.