That's not that impressive, even 1:1000 kills:losses is a positive ratio.
I assume they mean a ratio > 1.
And: this is a pretty incredible story. If you don't bother reading it all (it's not that long), at least read this bit:
> Exploiting thick fog and careless guards, Manfred Ramminger – a KGB-agent in West Germany – entered Neuburg air base during the evening of Oct. 22, 1967. Together with his Polish driver Josef Linowski and German F-104 Starfighter pilot Wolf-Diethard Knoppe, he stole an operational AIM-9 [sidewinder missile] from the local ammunition depot and transported it down the entire runway on a wheelbarrow to his Mercedes sedan, parked outside the base.
> The 2.9-meter-long missile proved unwieldy. Ramminger broke the rear window and covered the protruding part with a carpet. In order not to attract attention of the police, he then marked the protrusion with a piece of red cloth, as required by law.