Comrade Efimenko's only connection with the Soviet military was his time as a conscript in the early 1960's.  After leaving the military, he became a diesel-generator specialist.  In this capacity, he was sent to Vietnam in 1972, to service the generators powering the ring of surface-to-air missile sites around Hanoi.  During late December 1972, the US Air Force launched one of heaviest bombing campaigns of the Vietnam War... Operation Linebacker II. 

These missions were normally preceded by a 'Wild Weasel' strike- an air-to-surface strike on the missile sites to render them ineffective to the incoming wave of bombers.  On this particular day, one of the SAM sites was destroyed, along with it's power generation system.  The SAM sites around Hanoi had interconnected power systems, so the destruction of a vital power source would take down several launchers.

On site immediately after the air strike, Comrade Efimenko repaired the power system, just in time to shoot down two B-52 bombers returning from their mission over the city.  Searching through the wreckage the next day, he took the air system data plate as a 'souvenir'. 

Upon his return from Vietnam in May 1973, he was given his Vietnamese gallantry medal, the Vietnamese Friendship Medal, and the Soviet government awarded him with the medal "For Heroic Labor".

Additional photos of Efimenko's Group