Precision‐Guided Munitions

Precision‐Guided Munitions (PGMs) are generally characterized as weapons with terminal guidance systems. In addition to “smart” bombs, the term is applied to a wide variety of weapons, from air‐to‐air and air‐to‐ground missiles to wire‐guided torpedoes.

One of the most enduring images of the Persian Gulf War of 1991 are the videotapes played on CNN and other news networks of “smart” bombs in action. These tapes showed, from bomb‐mounted TV cameras, the munitions rapidly and accurately approaching their targets, followed by the picture turning black and then into static when it hit. This popular memory persists despite the fact that a mere 9 percent of the bombs dropped by the Americans during the conflict were of the “smart” type. Weapons such as these fall into the category of precision‐guided munitions.

Despite the publicity surrounding the “smart” bomb, antitank weapons are the type most associated with precision‐guided munitions. The Soviets had the best early success in the 1960s with their AT‐1, AT‐2, and most of all the AT‐3 “Sagger” antitank missiles. The United States had its start with anti‐armor PGMS in the 1970s with the first generation of TOW (tube‐launched, optically sighted, wire‐guided missile), ushering in a period of emphasis on PGMs. These two weapons systems saw their first widespread use in combat during the 1973 Yom Kippur War. Egyptian units equipped with Soviet AT‐3s destroyed 180 of 290 Israeli tanks in just one day of combat on the Sinai front. By the conclusion of the seven days of fighting, Israel had lost 420 tanks—25 percent of its inventory. This devastating result would not go unnoticed by military theorists.

The paramount driving force behind the development of PGMs is efficiency. The massive bombing campaigns and artillery barrages of World War II caused a great deal of collateral damage, but very often failed to destroy the intended target. The actual objectives of many of these attacks could have been neutralized using only a fraction of the explosive tonnage delivered, but the lack of an accurate delivery method required the use of “area bombing” with a large tonnage of munitions. This technique, along with specific targeting of civilians in “terror bombing” campaigns, was at best morally questionable. Furthermore, the belief that bombing would break the enemy's spirit to fight seems to have been unfounded.

The measurement used to determine bombing efficiency is known as circular error probable or CEP. The CEP is the radial distance from a target inscribing an imaginary circle with an area large enough so that 50 percent of the bombs dropped fall within it. The CEP during World War II was 3,300 feet; in the Vietnam War and the Persian Gulf War, it was 6 feet.

The drawback with PGM is cost. A iron “dumb” bomb or an unguided rocket is much less expensive than a precision‐guided bomb or missile. Concerns about the costs and reliability and the expenditure in training with these munitions were the subject of congressional hearings in 1984.

Although the Persian Gulf War of 1991 brought headlines to “smart” bomb PGMs, such weapons had been used by the United States five years before in a 1986 raid on Libya and nearly twenty years earlier in Vietnam. Primitive PGMs had even seen some use by Germany in World War II. It was in the Vietnam War, however, that PGMs saw their first success. One of the early PGMs was the navy's “Walleye” electro‐optic guided bomb (EGOB). The Walleye is little more than a TV camera mounted on the weapon's nose. As the munition descends, the television relays the bomb's view to a monitor viewed by a weapons officer who remotely steers the bomb electronically by controlling its tail fins. A U.S. Air Force approach, developed by Col. Joseph Short and Weldon Wood of Texas Instruments, involved laser energy. Known as “Paveway,” this laser‐guided bomb (LGB) involves an attacking aircraft that finds a target via a TV camera and then fires a “Pave Knife” laser designator to “paint” the object to hit. The bomb then follows the beam through a laser seeker unit. This technique required only a single aircraft, but when used against targets in North Vietnam, it was found to be more effective for two aircraft to conduct attacks. One would locate and designate the target while the other dropped the bomb. The first successful PGM attacks in North Vietnam using both Walleye and Paveway‐type munitions were against the Paul Dormier Bridge and Than Hoa Bridge in April and May of 1972.

The social and political ramifications of PGM—especially bombs and missiles—has been significant. Post–Gulf War punitive raids on Iraq, strikes on Serbian positions in Bosnia, and the 1998 U.S. retaliatory raids on terrorist facilities in Afghanistan and the Sudan have all been carried out with PGMs in order to minimize damage to civilians and risk to U.S. service people. “Standoff” weapons fitting into the PGM category provide the United States with the means to strike adversaries from a distance with little or no risk to U.S. forces.
[See also Bombing of Civilians; Bombs; Heat‐Seeking Technology; Lasers.]

David E. Michlovitz