The U.S. government's procedures for launching nuclear missiles are supposed to be airtight: the codes for unleashing the atomic might of the world's largest superpower are kept locked in a briefcase carried by an aide who accompanies the president at all times.
The codes for opening the briefcase, in turn, are inscribed on a plastic card carried by the president.
So what if that precious piece of plastic - nicknamed "the biscuit" in the bizarre jargon of the Secret Service - goes missing?
That's exactly what happened in 2000, during the administration of president Bill Clinton, writes General Hugh Shelton, the former chairman of the Joint Chiefs of Staff.
According to the Daily Telegraph and several other media outlets around the world, General Shelton's new memoir, Without Hesitation: The Odyssey of an American Warrior, reveals that no one could find the codes for several months in 2000. An aide finally admitted they had been lost.
"The codes were actually missing for months," he wrote. "That's a big deal - a gargantuan deal."
Perhaps more surprisingly, it may not have been the first time Mr. Clinton misplaced the free world's most important set of numbers.
Lieutenant Colonel Robert Patterson, one of the people tasked with toting the briefcase during Mr. Clinton's presidency, wrote in his own book seven years ago that the forgetful POTUS misplaced the card - which he apparently kept in his pants pockets with his credit cards - on two occasions.
The first time, he left it in the White House when he went to play a round of golf; the second time, in early 1998, aides turned the White House upside-down, and searched the president's clothes without finding them.
To be fair, Mr. Clinton may have had other things on his mind - the morning he lost the second codes was apparently the one on which the press broke a story about a former intern named Monica Lewinsky.