Why Terrorists Love Casio's Iconic F-91W Watch

The only thing you and Osama bin Laden are likely to have in common just turned 30.
Casio F-91W
A Casio F-91W. Photo by VICE UK.

This article originally appeared on VICE France.

Ripley wore a Casio F-91W in Alien, as did Obama before he became the president of the United States. Apparently, it’s also the only branded thing Osama bin Laden ever wore in public. Thirty years after its launch, Japanese watchmaker Casio is still producing 3 million units a year, meaning it's likely you've at least seen if not worn one too.

In the 1980s, new Casio recruits were made to attend ten days of army training before starting the job. The experience likely influenced Casio's Ryusuke Moriai when he designed the F-91W, described by him as “small, flat and simple”: the designer had unknowingly created the perfect combat watch.


Casio’s UK marketing manager claims the company doesn’t market the F-91W as “cool or trendy”, but as “reliable and good value”. Either way, Casio’s F-Series watches, once hailed as “wearable miracles”, have appealed to rebels around the world; they’re on the wrists of DJs, creatives, members of the Zapatista National Liberation Army and also French Islamic State fighters.


A metallic F-91W on the wrist of French Jihadist Abu Maryam Al-Faransi Chassin, in a screenshot from an Islamic State propaganda video broadcast in November 2015.

The F-91W’s availability and price (about £10 to £25 in Europe and £2.50 in the Middle East) goes some way to explaining its success. But the watch is also renowned for being one of Al-Qaeda’s favourite accessories: the terrorist organisation was even known to distribute them in training camps in Pakistan and Afghanistan.

Jihadi militants appreciated the F-91W and its dozens of variations for their resilience. Run it over with a car, smash it with a hammer, drop it in boiling or ice-cold water – the beast holds its own. You can generally trust terrorist organisations to pick reliable accessories – and much like Kalashnikovs and Toyota pickup trucks, the F-91W is sturdy, prolific, and cheap. It can also work as a key ingredient for bombs.

Specifically, the watch can reportedly come into play for the detonation of improvised explosive devices thanks to its long-lead timer, as NPR detailed in 2011. As such, the United States Department of Defense lists the watch as one of Al-Qaeda’s favoured IED triggers. Ahmed Ressam, or the “Millennium Bomber”, who planned to blow up Los Angeles airport on New Years Eve in 1999, was arrested with four bombs on him – all equipped with F-91Ws.


Described as a “genius" bomb manufacturer by a former US counter-terrorism expert, Al-Qaeda’s Ramzi Yousef was known for using the F-91W. The watch was so commonplace that Yousef was once able to use it to assemble a bomb in the toilet of a plane. Another former senior member of Al-Qaeda, Tariq al-Harzi apparently taught several wannabe terrorists to build similar ignition systems. He later topped the ranks of Islamic State.


A metallic model of the F-91W as worn by one member of the Syrian Democratic Forces, a military coalition whose main goal is to combat the Islamic State, on the Syrian front in early 2019. Screenshot: VICE News Tonight

United States Intelligence quickly noticed the prevalence of F-91Ws on the wrists of Islamist fighters. Secret files about the Guantanamo military detention camp published by Wikileaks say Pakistani authorities discovered some 600 to 700 Casios in two workshops in Karachi, and that simply owning one could warrant an interrogation. One prisoner’s evaluation sheet confirms “about a third of inmates at JTF-GTMO [the unit in charge of Guantanamo] who were captured wearing one of these watches had a known correlation with explosives”.

The problem is, F-91Ws are far too popular to actually incriminate a wearer, unlike the old SEGA cartridge-based detonators once favoured by Al-Qaeda. One alleged Al-Qaeda member captured by the US pointed this out, saying, "Your own military personnel also carry this watch. Does that mean that they’re just terrorists as well?″

Outside of the terrorist world, the F-91 W is popular in many regular armies, including in Singapore's military service, US AIR Force training camps, the British Army and the Royal Air Force. Its modest charms have also appealed to modders – hobbyists who love modifying objects from their original purpose. Modders inject mineral oil into the F-91W’s casing to make it more water resistant. One version, pimped with olive oil, apparently survived three days in a tank simulating a depth of 1000 metres.

Thirty years on, veteran Ryusake Moriai heads up watch design at Casio G-Shock. The brand is now known for bulkier designs more still inspired by combat: wider and tougher. The F91-W looks pretty harmless in comparison.