© Shiho Fukada/Associated Press
The U.S. military says Casio F-91W watches like this one have been used in terrorist bombings by members of al-Qaida, according to Guantanamo Bay files released by WikiLeaks.
It's a simple, water-resistant digital watch that retails for about $11. But beware: It could sell you out as al-Qaida.

A new batch of WikiLeaks files from Guantanamo Bay reveals a secret checklist U.S. investigators used to figure out whether detainees were really al-Qaida members. Among the criteria was the kind of wristwatch they were wearing.

The U.S. military lists the Casio F-91W model -- a cheap plastic watch available all over the world -- as a "suspicious item" on par with military transceivers, satellite phones, huge wads of cash and secret notes from al-Qaida facilitators. According to a confidential document distributed to American interrogators at the Guantanamo Bay prison, the Casio model "is an indicator of al-Qaida training in the manufacture of improved explosive devices (IEDs)."

"The Casio was known to be given to the students at al-Qaida bomb-making training courses in Afghanistan, at which the students received instruction in the preparation of timing devices using the watch," the document states.

One-third of detainees captured while wearing the Casio watch "have known connections to explosives," it said.

The memo was used to train U.S. investigators on how to accurately gauge the threat level of certain detainees at the U.S. terror prison in Cuba. More than 50 reports about individual detainees mention the Casio watch, along with a slightly more expensive model, the A-159W, made of stainless steel.

Millions of innocent people around the world are believed to wear the Casio F-91W. But the idea that it could be used by al-Qaida was first revealed in 2006, after The Associated Press sued the U.S. government to make public transcripts of U.S. military tribunals at Guantanamo.

One transcript reveals how U.S. military interrogators kept questioning one detainee, a Kuwaiti engineer, about his Casio watch. According to the German newspaper Der Spiegel, which republished an excerpt of the transcript, the Kuwaiti man expressed surprise when told that his wristwatch could link him to al-Qaida.

"We have two watches in Kuwait: Fossil and Casio. This watch has a compass that shows the direction of Mecca. I am Muslim and pray five times a day," the man explained.

In fact, he said all four Muslim chaplains working at Guantanamo at the time of his interrogation also had the same Casio watch to identify the direction in which to pray.

"I swear I don't know if terrorists use it or if they make explosives with it," the Kuwaiti detainee said. "If I had known that, I would have thrown it away. I'm not stupid."

The man's name wasn't revealed, and it's unclear whether he was released or is still being held.

There's been no public comment from the Casio company about the U.S. allegations, and it's unclear whether they've affected sales.