Special codes that allow the US president to order a nuclear attack went missing "for months" during Bill Clinton's time at the White House, his former top military officer says in a memoir.

The nuclear authorization codes, known as the "biscuit," are supposed to remain close to the US president at all times and are safeguarded by one of his aides.

"At one point during the Clinton administration -- and until this day, to my knowledge this has never been released -- the codes were actually missing for months," former chairman of the Joint Chiefs of Staff Hugh Shelton wrote in his newly-published memoir, "Without Hesitation: The Odyssey of an American Warrior."

"This is a big deal -- a gargantuan deal -- and we dodged a silver bullet."

The aide assigned the sensitive job of keeping the "biscuit" managed to lose track of the codes in 2000, the retired general said.

When a colleague from the Pentagon came to the White House to confirm the codes as part of a monthly routine procedure, the aide put him off, saying Clinton had the codes and was busy with an urgent meeting.

"This comedy of errors went on, without President Clinton's knowledge I'm sure," Shelton said, until it was time to replace the codes with a new set, which is done every four months.

"At this point we learned that the aide had no idea where the old ones were, because they had been missing for months.

"The president never did have them, but he assumed, I'm sure, that the aide had them like he was supposed to," he added.

When he learned of the disaster, Shelton rushed to the offices of then-defense secretary William Cohen, saying: "you are not going to believe this."

Procedures were changed after the incident and fears that the slip-up would find its way on to the front page never materialized.

But the episode showed that no system could be entirely safe from human error, Shelton wrote.

"You can do whatever you can and think you have an infallible system, but somehow someone always seems to find a way to screw it up," he said.

Another book published several years ago described a similar incident, but alleged the episode occurred in 1998 the day after the Monica Lewinsky scandal broke.

Retired US Air Force lieutenant colonel Robert Patterson wrote that Clinton, and not an aide, allegedly lost track of the codes.

earlier related report
Radical Al-Qaeda cleric lunched at Pentagon: US
Washington (AFP) Oct 20, 2010 - Anwar al-Awlaqi, an Al-Qaeda leader labeled a dangerous threat by the United States, was invited to a luncheon at the Pentagon in the months after the 9/11 attacks, the US military said Wednesday.

Awlaqi, a Yemeni-American cleric, was brought to the Pentagon as part of an effort by the office of the secretary of defense (OSD) to reach out to the Muslim community after the September 11, 2001 attacks, military spokesman Colonel Dave Lapan told AFP.

"Our understanding thus far is that this was an informal outreach conducted by part of the OSD staff in the aftermath of 9/11 in an effort to gain a better understanding of Islam," Lapan said.

The account of the lunch with military officers and defense officials was first reported by Fox News, which cited FBI documents and sources.

President Barack Obama's administration has authorized the targeted killing of Awlaqi, an American citizen who US officials believe is linked to three plots against the United States, including a shooting rampage at Fort Hood last year, a failed bid to blow up a US-bound airliner on Christmas Day and an attempt to set off a car bomb in New York's Times Square.

A current employee of the Defense Department told the FBI last year that she had helped arrange the invitation after hearing Awlaqi speak in Alexandria, Virginia.

The employee "recalls being impressed by this imam. He condemned Al-Qaeda and the terrorist attacks," according to an FBI document posted online by Fox News.

At that time, the then-secretary of the US Army was interested in having a "moderate Muslim" speak to a Pentagon audience, said the FBI document.

Awlaqi came under FBI scrutiny after the 9/11 attacks because of his ties to some of the hijackers.

But Pentagon officials who approved the lunch invitation were apparently unaware of the FBI's interest in Awlaqi.

The Pentagon employee was interviewed by the FBI as part of the investigation into the Fort Hood shooting, which left 13 people dead.

Now based in Yemen, Awlaqi rose to prominence last year after it emerged he had communicated extensively by email with Major Nidal Hasan, the US Army psychiatrist accused of opening fire on colleagues at Fort Hood.

Awlaqi has praised the Fort Hood rampage and said Muslims like Hasan should only serve in the US military if they planned to carry out similar attacks.