BOGOTA, Colombia (AP) -- Made in the USA in the 1970s. Shipped to a
                 Central American government fighting leftist rebels. Stolen in 1992 as
                 part of an assassination plot against a drug kingpin.

                 And planted last week by right-wing paramilitaries next to a communist
                 newspaper's offices in Bogota -- the journey of a U.S. Air Force bomb from an
                 ammo depot in Oklahoma to Colombia traces the violent history of this country,
                 and serves as a cautionary tale about where sophisticated munitions can wind
                 up if they are not guarded carefully.

                 The yellow 500-pound bomb, discovered May 21 by a security guard, is not a
                 medium-level explosive like the two that blew up in the capital on Friday, killing
                 four people and injuring 26.

                 This one, more than six feet long, is built for devastating effect. If it had gone
                 off, police said, it would have blown two city blocks to bits -- the worst
                 terrorist attack in Colombia in more than a decade.

                 The bomb, known as an MK-82, is favored by many air forces in the world
                 "where maximum blast and explosive effects are desired," according to literature
                 on the device.

                 Part of the bomb's history can be traced by the numbers engraved into it,
                 including 0473, which shows it was made in April 1973, according to Cathy
                 Partusch of the Naval Aviation Systems Team in Patuxent River Naval Air
                 Station, Maryland. She confirmed the device was a U.S. Air Force bomb.

                 It was delivered in January 1974 to what was then known as the U.S. Naval
                 Ammunition Depot, now called the Army Ammunition Plant, in McAlester,
                 Oklahoma, said Capt. Almarah Belk, a U.S. Air Force spokeswoman at the
                 Pentagon.

                 Belk said that because the bomb is so old, records are difficult to trace on
                 where it was delivered next, and that it was more than likely part of an arms
                 sale.

                 In fact, it appears to have been sent to El Salvador, part of a U.S. military
                 assistance package to the Central American country, which battled leftist rebels
                 from the late 1970s until 1992.

                 In 1992, the Cali cocaine cartel -- named after Colombia's third-largest city --
                 bought four bombs from corrupt Salvadoran air force officers, the Salvadoran
                 armed forces said at the time. The purpose: to kill Pablo Escobar, the Cali
                 cartel's rival who was imprisoned near Colombia's second city of Medellin.

                 The plotters intended to kill Escobar -- boss of the Medellin drug cartel -- by
                 dropping the four 500-pound bombs from helicopters onto the prison,
                 according to El Salvador's top drug-fighting agency, the Executive
                 Anti-Narcotics Unit.

                 Salvadoran agents busted up the plot, arrested nine people -- including three
                 Salvador air force members -- seized one of the bombs and confiscated almost
                 $500,000.

                 But the agents acted too late to prevent three of the bombs from being loaded
                 aboard a plane and flown out of El Salvador from a remote coastal airstrip.

                 The Cali cartel abandoned its assassination plot after Colombian authorities
                 banned air traffic over Escobar's prison and installed anti-aircraft guns.

                 Months later, Escobar escaped from prison, and was killed by police in a gun
                 battle in December 1993. The Cali cartel chieftains wound up being arrested or
                 slain in later years.

                 Meanwhile, no one knew where any of the three missing bombs were -- until
                 May 21.

                 The commander of Colombia's air force, Gen. Hector Fabio Velasco, confirmed
                 last week that the bomb planted outside the communist newspaper, Voz, is one
                 of the bombs.

                 Carlos Castano, head of a right-wing paramilitary army which during the 1990s
                 supported the Cali cartel's war against Escobar, acknowledged his outfit had
                 buried the bomb under a load of bananas and oranges in the back of a pickup
                 truck, and parked it in front of the communist newspaper's offices.

                 After the bomb was discovered last week, police announced they had disarmed
                 it. But explosives experts later said the bomb posed no immediate threat -- that it
                 could not have detonated without having been dropped from a great height.

                 Castano told Colombian media on Friday that his United Self-Defense Forces of
                 Colombia planted the bomb as a warning to Voz's publisher, Carlos Lozano --
                 recently named to a government peace commission -- to tread carefully.

                 Of concern is that two missing MK-82 bombs may still be somewhere in
                 Colombia, a violence-wracked nation where mass killings are common. But
                 also, the paramilitaries might now get their hands on weaponry from the United
                 States in a more direct fashion.

                 Washington is currently delivering millions of dollars in military assistance to
                 Colombia to fight leftist rebels and drug traffickers. The Colombian government
                 is also cracking down on United Self Defense Forces of Colombia, but the
                 paramilitary group maintains covert links with elements in Colombia's armed
                 forces.

                 "We already know there's information sharing, that there's communications
                 between various Colombian army units and paramilitaries, and coordination in
                 the field," said Robin Kirk of Human Rights Watch/Americas.

                 "It doesn't take a whole lot of imagination to imagine that weaponry the United
                 States is sending would also make it into the hands of the paramilitaries," Kirk
                 said.

                   Copyright 2001 The Associated Press.