The introduction of crossbows onto West European battlefields in the 10th and 11th centuries bestowed unsophisticated foot soldiers with an easy-to-use, highly lethal weapon. By penetrating the mail of armored knights, the crossbow, for the first time, rendered these fearsome, highly-trained warriors vulnerable. Reports being received form the battlefields of Western-supported insurgencies clearly show the impact of a modern ``crossbow'' - the American-made, hand-held, surface-to-air missile called the Stinger. Its effect, like its medieval counterpart, is to enhance the capabilities of irregular infantry against better-equipped opponents.
The shoulder-fired, heat-seeking Stinger is highly resistant to jamming. Relatively inexpensive, it is superior to earlier weapons of its type - the Soviet SA-7 and the American-made Redeye.
During 1986, the Reagan administration provided Stingers to anticommunist Afghan and Angolan guerrillas. For years, a principal weakness of Afghan and Angolan guerrillas has been inadequate air defenses. But recent figures suggest the Stinger has helped the rebel National Union for the Total Independence of Angola (UNITA) overcome this weakness. The figures, cited by UNITA and confirmed by independent analysts, signify a radical rise in insurgent air defense capabilities directly traceable to the Stinger.
Between January 1986 and April 4, 1987, UNITA shot down 65 aircraft flown by the Marxist Angolan government forces, their Cuban protectors, or the Soviets. This figure includes not only relatively slow transport planes, but 26 jet fighters as well as 32 helicopters. UNITA calculates the value of these downed aircraft at about $500 million.
A somewhat slackened pace on the part of UNITA's Angolan, Cuban, and Soviet opponents - induced by the Stinger threat - has also been noted by insurgents during recent months. And to guerrillas in the field, the freedom of movement permitted by this decreased air activity is as meaningful as the actual ``kills'' themselves.
Similar reports have filtered out of Afghanistan, where Western-supported mujahideen, as the Afghan resistance fighters are known, are carrying on a protracted war against Soviet and Afghan government forces. According to unconfirmed published accounts, dozens of Afghan or Soviet planes and helicopters have been downed by Stingers.
The implications of this situation are profound in terms of the ability to sustain an insurgency. It means that Soviet-provided aircraft cannot be utilized with impunity as a substitute for artillery in hard-to-reach areas. It signifies heightened danger for air mobile forces operating in guerrilla-infested zones. And it gives an immediate psychological boost to the fighters.
In other words, we may be witnessing a change in low intensity warfare in these two countries. This may signify that the indispensable air superiority of professional armies over insurgents is partially neutralized. There is a relatively high impact of a fairly small dollar value of military assistance from the United States.
Like the crossbow, this advantage will not last forever. Countermeasures will be devised. And some missiles could end up on the black market or in the hands of terrorists. But for a time, the armored knight of today's conventional counterinsurgency forces has become vulnerable.
The writer was a government official for two decades before becoming a consultant on international affairs.