The explosions and fires that killed almost 70 people aboard an India-to-Pakistan passenger train late Feb. 18 were caused by timed incendiary devices (TIDs), rather than by much more commonly used improvised explosive devices (IEDs), according to Indian investigators' description of the devices. The success of the attack, combined with the ease of assembling the components for TIDs, portends similar attacks against India's highly vulnerable mass transit system by militants
out to destroy any progress toward peace between the South Asian neighbors. Moreover, the use of TIDs easily could spread elsewhere. The blasts occurred at about midnight local time on India's Samjhauta (Friendship) Express, which in 2004 became the first communication link between India and Pakistan in two years after relations between the countries thawed. Because of the important symbolism of the train, it has become an attractive target for militants. However, this appears to be the first time TIDs have been used in a major attack against the country's rail system. Explosive-actuated TIDs — more commonly called firebombs — work by using a relatively small low-intensity explosive charge to ignite a more volatile flammable material. This results in an intense, rapidly spreading fire that quickly can engulf a confined space such as a rail car, subway car or airplane. In this case, Indian forensic experts described the devices as being composed of sulfur, potassium nitrate and kerosene. Sulfur, potassium nitrate and charcoal are the chemical components of black powder, which is easily ignited. The black powder, then, appears to have functioned as the explosive, which tore through plastic bottles containing kerosene and ignited the fuel. The process likely involved the use of commercially available chemical pencil timers — pencil-shaped casings that contain a vial of acid and safety wire. Once the vial is broken, the acid eats through the wire, which then releases a spring-loaded firing pin and activates the igniter, which in this case probably was a pipe bomb filled with the black powder. The time delay of the device can be varied from a few minutes to an entire day, depending on the diameter of the wire used. Indian authorities believe a total of four TIDs were planted in suitcases on the train, though two failed to detonate and were recovered and defused. More than a dozen plastic bottles containing the flammable material were packed next to the timers and igniters inside each suitcase. Because rail transit, especially commuter rail traffic, has higher passenger volume and less security screening than air travel, it is more vulnerable to attack
by militant groups. Moreover, when fire codes and safety regulations on mass transit are lax or poorly enforced, and trains might be overcrowded, the effect of a TID attack can be amplified. In this latest attack, even though metal detectors were used to screen passengers, luggage was not checked, allowing the perpetrators to get the devices aboard the train. The death toll probably was further increased because the bars over the train coaches' windows prevented easy escape after the blaze started. Trains frequently are attacked in India, although all of the major bombings since 1996 — including the July 2006 Mumbai commuter train attack — have involved IEDs utilizing high explosives such as RDX. However, whereas RDX can be difficult to manufacture or purchase, anyone can acquire gasoline or kerosene. There also are a great many ways to make TIDs, some of which do not even require the use of black powder. Although this appears to be the first TID attack against India's rail system, the technology in these timers is not new. German army plotters, for example, used a similar device in an attempt to assassinate Adolf Hitler in July 1944. Furthermore, similar attacks using TIDs
were attempted on trains traveling in western Germany in August 2006, though the devices failed to ignite. Four people were taken into custody in Lebanon and Germany in connection with the potentially devastating plot. Although the attack in Germany failed, this latest firebombing sets a potentially dangerous precedent, especially since TIDs can be more easily constructed — and with more readily available materials — than more complex high-explosive IEDs. This type of attack likely will be copied elsewhere in India — and beyond.