“The objective of the plan was two fold — thin the enemy’s ranks, while at the same time sapping his confidence in his own equipment.”
THE U.S. MILITARY’S Studies and Information Group might sound like a dull Washington policy think thank, but during the Vietnam War, the SOG planned and carried out some of the most daring, not to mention devious, operations of the long and bloody conflict.
Case in point: Beginning in 1967, the notorious unconventional warfare unit flooded communist ammo depots throughout Southeast Asia with thousands of sabotaged rifle, machine gun and mortar rounds. Each of the ordinary looking bullets was packed with enough high explosives to destroy any weapon that fired it while also maiming (or perhaps even killing) the unlucky shooter. Charges hidden within spiked mortar shells were powerful enough to wipe out an entire gun crew.
The objective of the scheme was two fold: thin the enemy’s ranks and sapping his confidence in his own equipment.
It was a 45-year-old SOG colonel named John Singlaub who first suggested the ploy. The former OSS operative supposedly borrowed the idea from the British army, which had secretly distributed its own exploding .303 Lee Enfield rifle rounds to enemy rebels in Waziristan during the 1930s and even tribal insurgents in Zimbabwe as early as the 1890s. 
The American plan, dubbed Project Eldest Son, called for technicians to pry apart thousands of captured AK-47 and 12.7 mm machine gun rounds, as well as 82 mm mortar shells and fill the casings with a potent explosive that was virtually indistinguishable from conventional gunpowder. The booby trapped munitions were then reassembled and mixed into crates of perfectly good ammo bound for enemy supply depots. Eventually, the SOG manufactured more than 12,000 trick rifle bullets and machine gun rounds along with nearly 2,000 killer mortar shells.
Over a two-year period, U.S. special ops teams fanned out across South Vietnam, Laos and Cambodia covertly depositing ammo crates containing the corrupted rounds into enemy supply caches. Another tactic was to leave full magazines loaded with a single tainted bullet onto battlefields in hopes the ammunition would be recovered and used by North Vietnamese forces or communist guerrillas.
At the same time, the SOG spread rumours of Chinese armaments factories producing faulty munitions. According to some of these planted stories, deficient ammo was knowingly being transferred to communist troops in Vietnam by careless and indifferent government officials in Beijing. It was hoped that the narrative might lead to a rift between the two communist powers. The U.S. Armed Forces Radio Network, which was routinely monitored by enemy intelligence, added to the disinformation by advising GIs to avoid using captured weapons because of the risk posed by defective Chinese bullets. 
The SOG even went so far as to forge official looking VC and NVA communiqués reporting the hazardous ammunition. The bogus documents were dropped in the field for enemy units to recover and pass along to their superiors.
Little data exists as to the success of the operation. Eventually, Eldest Son had to be abandoned in 1969 when details of it were leaked to the American media. The story didn’t end there however.
It’s been reported recently that the Syrian state military has launched a similar operation its long-running civil war against various rebel groups. According to the New York Times, pro-Assad forces have been secretly passing booby-trapped rounds to enemy fighters via illegal arms bazaars across the region. The paper reports that Damascus appropriated the idea from the U.S. military, which had reportedly been booby trapping insurgent bullets in both Afghanistan and Iraq.
(Originally published Nov. 13, 2013)