equivalent of the CIA
The ultimate "dirty tricks" organization.
AKA Cheka 1917; NKVD in 1922; OGPU in 1923; NKVD in 1934; NKGB '41, NKVD later that year; NKGB in '43; MGB in '46; MVD in '53; finally settled on KGB in '54. Currently known as SVR, but don't be fooled, it's the same organization from the beginning down to today.
Assassination? Yep. Ukrainian dissident Lev Rebet was killed with a poison mist gun in 1957 by assassin Bogdan Stashinski. Trotsky, of course, was killed in Mexico by Ramon Mercader, with an icepick, but only after he survived a hail of bullets through his bedroom window. Of course, the political assassinations were nothing compared to the Gulag deaths, but that's another node. Eventually, assassinations went out of vogue since the assassins had a nasty habit of defecting and confessing, and were replaced with incarcerations and "accidents", or simply inhumane conditions that did the same thing.
Espionage? Of course. Some highlights:
The Soviet nuclear program was lifted completely from the American; the first Russian bomb was identical in every way to the first American nuclear bomb detonated in Almagordo down to the rivets. Blame Julius and Ethel Rosenberg for that one, but they weren't the only KGB moles in America.
For years, every word uttered in the American Embassy in Moscow was overheard by the KGB. They even had a bug inside the Great Seal of the United States behind the Ambassador's desk. From 1969 to 1973, the table in the US Senate Foreign Relations Committee conference room hid a voice activated radio transmitter from our Russian friends.
Moles? They had an entire division that would create fake identities, infiltrate agents in foreign countries, and wait YEARS for an opportunity to become useful. For example: Vilyam Fisher lived from 1948 to 1956 under a variety of aliases in the US. He was a house painter, an artist, and socialite, and a few other careers. He was eventually caught and exchanged in a spy swap for downed aviator Gary Powers. It is no exaggeration to say that at any one time they had thousands of agents in every level of society operating in Europe, and certainly hundreds in the US.
Of course, most spies for the KGB weren't Russian, they were traitors. In the United states, for example, Larry Duggan (head of the State department's Latin American section during FDR's third term) and Harry White (third man in FDR's Treasury department) were both agents for the KGB. Never heard their names? Henry Wallace, FDR's VP during his third term, said if FDR had died while he was VP he would have made Duggan secretary of State and White secretary of the treasury. Close call.
Other American KGB agents included: Michael Straight (KGB code name NIGEL), form the State department; Martha Dodd Stern (LIZA), daughter of the US Ambassador to Germany; William Doss (PRESIDENT) who ran for congress and, luckily, failed; Boris Morros (FROST), who directed Laurel and Hardy's "Flying Deuces"; and Henry Buchman (KHOSAIN), who owned a woman's fashion salon in Baltimore. The Red Scare wasn't just paranoia.
Just the tip of the Iceberg.
And how was all this discovered? There was only one man who saw EVERY SINGLE DOCUMENT AND REPORT produced by the KGB. Vasili Mitrokhin was the chief KGB archivist, and probably the only man who saw every report without political whitewash. He also photocopied *EVERY* paper that crossed his desk and smuggled them out in 1992.
Read about it in "The Sword and The Shield" by Christopher Andrew and Vasili Mitrokhin.