The Sovs have always had rather a robust response to terrorism.
On September 30, 1985, four Soviet diplomats were kidnapped by the Islamic Liberation Organization in Beirut. One, Arkady Katkov, was killed by his captors while trying to escape. The other three, commercial attache Valery Mirkov, press attache Oleg Spirin and embassy doctor Nikolai Seversky, were released unharmed a month later after a relative of the terrorist leader's was kidnapped and killed by the Soviet KGB.
The terrorist leader's relative was actually his four-year-old son. A Spetsnaz team took the boy from his home. They then delivered the boy’s cut off ear to his mother with a video of the cutting. On the video was a message that if the remaining three Soviets were not released unharmed, the next video would be of the boy’s castration. The Soviets promised that if the diplomats were released, the boy would not be castrated.
The remaining diplomats were released. The Soviets then simply shot the boy in the back of the head in retaliation for the murder of Katkov. However, the KGB did keep its promise and the dead boy was not castrated.
After that, no Soviet diplomat in Lebanon was ever threatened again.