One of Russia's highest ranking spies and the powerful head of military intelligence has died “after a long and serious illness,” a Defense Ministry spokesperson told the news agency RIA Novosti. Gen. Col. Igor Korobov, the 63-year old head of Russia’s Military Intelligence Directorate (GRU), was reported dead early Thursday morning; currently there's no reports of foul play though officials did not reveal specific details or the circumstances of his death.

Crucially Korobov had been dubbed by the West the "Novichok spymaster" — as the Russian GRU chief ultimately blamed for the Salisbury attack as well as the downing of MH17 over Ukraine in 2014, which the Kremlin in turn had blamed on pro-Kiev national forces.

GRU director Igor Korobov, via The Daily Mail

Korobov had for two years been under US sanctions, added by US Treasury in December 2016 related to allegations of Russian hacking and “efforts to undermine democracy”. Ironically, however, he was seen at times as a cooperative ally in Washington's "war on terror" efforts since 9/11. In one particular stunning and unprecedented case, he was still allowed to participate as part of a high level Russian intelligence delegation to the United States in February 2018 to meet with American intelligence officials to discuss counter-terror initiatives.

At that time Korobov made the trip to D.C. despite officially being under US sanctions while accompanied by the directors of Russia’s Federal Security Service (FSB) and Foreign Intelligence Service (SVR).

According Korobov's bio in Meduza he ascended the ranks of the USSR's military intelligence wing starting in the 1980's:

He served in the Soviet and Russian armed forces since 1973, joining the USSR's military intelligence in 1985 and becoming Russia's GRU director in 2016. A career intelligence officer who started out in the 1980s, Korobov graduated from the “Conservatory” and went on to oversee Russia’s strategic intelligence gathering, including the management of all foreign stations. His appointment was no surprise: since the 1990s, the president has traditionally entrusted the job to lieutenants who supervised Russia’s foreign stations.

According to TASS, "in 2016 he was appointed by a presidential decree as the head of the Main Directorate of the General Staff of the Russian Armed Forces and Deputy Chief of General Staff of the Russian Armed Forces."

Korobov had been ill since early October, when reports revealed he was severely reprimanded by President Putin himself over mishandling accusations surrounding the alleged Salisbury poison attack the West pinned on Russian intelligence.

According to The Daily Mail:

President Vladimir Putin personally gave a dressing down to the head of Russian spy agency GRU over 'deep incompetence' shown in the Salisbury poisonings and other international operations. GRU chief Col-Gen Igor Korobov, 62, reportedly emerged shaken and in sudden 'ill health' after his confrontation with the furious Russian president.

This detail alone means we could soon hear more to the story and circumstances surrounding his death, which the defense ministry has yet to be forthcoming about in terms of details or exact cause of death.

An official defense ministry statement called Korobov “a wonderful person, a faithful son of Russia and a patriot of his homeland.”