WASHINGTON -- The chemical weapons discovered by U.N. inspectors in an Iraqi warehouse Thursday have a simple, durable design and are intended to frighten and demoralize enemy troops as well as kill them.
The 122-millimeter rockets with chemical warheads can carry their deadly agents in gas or liquid form. They are usually fired in volleys of dozens of rockets at a time, to try to ensure that enemy troops are enveloped in a thick concentration of chemicals.
U.S. officials believe that the Iraqis have stores of lethal sarin gas, as well as VX, a heavy liquid that disperses in oily droplets that would cling to troops' skin, clothing and equipment. The Iraqis also know how to use blistering agents, such as mustard gas, and choking agents, such as chlorine gas, said Jon Wolfsthal, a nonproliferation expert at the Carnegie Endowment for International Peace.
Tim Brown, a senior analyst at GlobalSecurity.org, a Washington-area defense consultant, said the chemicals are loaded into a hollow outer casing of the rocket. The explosives are inserted in an inner core, and the fuse is placed in the nose.
The rockets are fired when the operator sets off a propellant charge in the tail. When the warhead reaches a certain altitude or distance toward the target, the fuse sets off the explosives, releasing the chemicals. Stabilizing fins keep the rockets on a straight trajectory. They have a range of up to 12 miles.
The rockets follow a Soviet design that has been widely copied. The basic technology dates to World War II.
It can be tricky to use the weapons effectively. If the chemicals are released at too high an altitude, or in too much wind, they will disperse and do little harm, experts say.
The Iraqis have "weaponized" chemicals in artillery and mortar shells, aerial bombs and grenades. But rockets offer the best way to mount a highly concentrated chemical attack, Brown said, because a rocket launcher can carry as many as 40 rockets.
Unlike conventional rockets and artillery shells, chemical warheads have a relatively thin outer wall. When they explode, they make a low thudding sound that is noticeably different from the loud report of a conventional shell, and is easily identifiable by troops on the battlefield.
Brown said the use of chemical weapons can quickly panic troops on the battlefield, making it difficult for them to carry on and operate their complex weapons and equipment.
The Iraqi army is the most experienced in the world in the use of chemical weapons. Iraq fired thousands of chemical rockets and artillery shells at Iran during their 1980-88 war, inflicting an estimated 50,000 casualties, including untold thousands of deaths, on Iranian troops and civilians.
Saddam Hussein's attack on Iraqi Kurds in the city of Halabja in 1988 is believed to be the biggest single chemical assault on a civilian population in modern times. Five thousand ethnic Kurds died.
The Iraqis didn't attack U.S. troops with chemical weapons during the 1991 Persian Gulf War, yet some U.S. veterans blamed chemical weapons releases for the unexplained ailments that cropped up among veterans after the conflict. About 60,000 U.S. troops have filed claims for injuries from that war.