The current chief of the intelligence arm of the Armed Forces of the Russian Federation has met an untimely death -- as did his predecessor.

The sudden death of Colonel General Igor Korobov, 62, on Nov. 21 after "a serious and long illness," was revealed by an official statement from the Ministry of Defense. Russian dictator Vladimir Putin expressed his condolences to Gen. Korobov's relatives in a statement. He said Gen. Korobov led "a "legendary agency."

The loving memory of this wonderful person, "a true son of Russia, a patriot of the Fatherland Colonel General Igor Valentinovich Korobov will always be in our hearts," said the defense ministry.

Speculation has it Gen. Korobov had run afoul Putin, who summoned him after the Skripal affair. Putin is also said to have severely criticized the operation that left the Skripals alive and the GRU a target of mockery in the Western media.

Gen. Korobov was absent from a ceremony in Moscow this month where Putin and other senior officials celebrated the centenary of the GRU. Putin praised the GRU's skill and "unique abilities" but without the presence of Gen. Korobov.

Gen. Korobov's official position was Chief of the Main Directorate of the General Staff of the Armed Forces of the Russian Federation. This spy agency is the successor to the Soviet-era GRU (Glavnoye Razvedyvatel'noye Upravleniye).

The Main Directorate of the General Staff of the Armed Forces of the Russian Federation is still widely referred to as the GRU.

Gen. Korobov is notorious among Western intelligence circles. He was the man responsible for the failed assassination attempt on Sergei Skripal last March in the United Kingdom. He was also a motive force behind Russia's interference in the U.S. 2016 presidential election. Both of these operations became huge political embarrassments to Russia and Putin.

The UK accused Russian operatives working for Gen. Korobov of poisoning Skripal, who worked as a spy for the British, and his daughter, Yulia, with a nerve agent. The Netherlands accused the GRU of trying to hack the global chemical weapons watchdog. The U.S. Intelligence Community said the GRU led Russia's intervention on the side of Donald Trump in the 2016 presidential election.

Gen. Korobov's predecessor, Col. Gen. Igor Sergun, also died at a relatively young age and also in suspicious circumstances. The Kremlin said Gen. Sergun "died unexpectedly on 3 January 2016, aged 59," but without citing the place and cause of his death.

One Western media outlet's report on Gen. Sergun's death said the ″circumstances of his death (were) not clear." One theory said Gen. Sergun was assassinated by Muslim terrorists during a botched secret mission in Lebanon.

The state news agency TASS cited a military source as saying Vice-Admiral Igor Kostyukov, the agency's first deputy head, had been standing in for Gen. Korobov during his "illness" and was favorite to formally succeed him.