October 17, 2011
Project Eldest Son: Covert Ammo Sabotage in Vietnam
By Phil Bourjaily
A few posts ago Mike55 asked if anyone else had read about the special forces operation in Viet Nam in which our troops slipped exploding cartridges into enemy ammo supplies. He was referring to Project Eldest Son, which, from a Gun Nut perspective, is the most fascinating covert operation ever. I cannot improve on this account of Eldest Son written by Major John Plaster, who participated, but in the meantime, here’s the Cliff Notes version:
In 1967, the Joint Chiefs approved of a plan to booby trap ammunition dumps found by Studies and Observation Group (SOG) teams in Laos by leaving exploding ammunition behind. The trick had been used in colonial wars by British troops who let booby trapped .303 ammunition fall into Pathan hands on India’s Northwest Frontier.
The idea of Eldest Son was not to kill large numbers of the enemy but to destroy confidence in their Chinese-made arms and ammunition. After CIA ordnance techs proved it was feasible to load a 7.62x39mm round with enough high explosive to drive the bolt back into the skull of the soldier firing the weapon, the work of sabotaging thousands of rounds began. It took a month for the CIA to pry bullets from captured ammo, replace the powder with an identical-looking, HE substitute, then reseat the bullets and reseal ammo cans and crates so there was no sign of tampering. The sabotaged rounds generated up to 250,000 psi, more than five times the pressure of a normal 7.62x39mm round and enough to blow up the weapon. Several hundred 12.7 mm machine gun rounds and nearly 2000 82mm mortar rounds were booby-trapped as well, the latter being designed to explode when they hit the mortar tube’s firing pin.
Green Berets carried booby trapped rounds with them and slipped them into enemy ammunition caches whenever possible. They would also load them into the magazines of rifles found near dead enemy soldiers. They were always careful to leave just one round at a time so all the evidence of sabotage would be destroyed when the round was fired. When the ammo turned up in the front lines, weapons began exploding, killing enemy riflemen and sometimes entire mortar crews. Then, the second part of Eldest Son kicked in: the dissemination of forged Chinese and NVA documents about the problem as well as U.S. intelligence briefs designed to fall into enemy hands. One bogus enemy report read “We know that it is rumored some of the ammunition has exploded in the AK-47. This report is greatly exaggerated. It is a very, very small percentage of the ammunition that has exploded." There were even Armed Forces Radio and TV PSAs about the dangers of using captured weapons due to their “faulty metallurgy” which were, of course, meant for the enemy to overhear.
Eldest Son was compromised when its details appeared in US press in 1969. The name was changed to Project Italian Green, and later, to Pole Bean and the rest of the ammunition was quickly placed in ammo caches, although without the leave-no-trace finesse of the Eldest Son operations. Nevertheless, even when the enemy knew the dump had been tampered with, it was nearly impossible to detect which round was booby-trapped so Italian Green and Pole Bean also succeeded in sowing seeds of doubt.