During a recent live fire exercise in Bulgaria, a 2K12 Russian anti-aircraft missile exploded shortly after launch. The president of Bulgaria was only 500 meters away, but was uninjured. He was, however, reminded that many of the weapons and munitions used by the Bulgarian military are elderly Russian made items.
Take the 2K12 (known as the SA-6 in the West). It entered service in 1970, and made a reputation for itself by shooting down most of the 102 warplanes the Israelis lost in the 1973 war. The SA-6 went through improvements over the years, but production ceased in 1985. The missiles required careful storage and maintenance, which they often didn't get in the many nations the Russians sold the system to. Many users have discarded the system, but about twenty nations still have it.
Accidents and failures are increasingly common with SA-6 radars and missiles (not to mention the tracked vehicles that carry, and launch, three missiles each). Russia (which no longer uses the SA-6, except as a target for more modern systems) had a long tradition of rarely throwing weapons or munitions away. If possible, the older stuff was sold off to foreign customers, at bargain rates. But these weapons were no bargain if there was a war, for the failure rate was very high. As the Bulgarians were just reminded.