Russian Ambassador to the United Nations Vitaly Churkin died unexpectedly on Feb. 20 after collapsing in his New York City office.
The Russian Foreign Ministry announced the news but stated that his cause of death is not yet known, reports WPIX.
"The outstanding Russian diplomat died while he was in his current working role," the Russian Foreign Ministry said in its statement. "We offer our condolences to the relatives of Vitaly Ivanovich Churkin."
According to law enforcement, Churkin was taken to a New York hospital in cardiac arrest, notes CNN. He had been working at his office at Russia's U.N. mission when he was taken ill.
The ambassador, who died one day before his 65th birthday, was regarded as a diplomatic giant and known for his keen wit and frequently blunt comments, especially toward America and the West. He was well-respected among his peers, even those with whom he had sharp and frequent disagreements.
"In my short time at the United Nations, Ambassador Vitaly Churkin showed himself to be a gracious colleague," new U.S. Ambassador to the U.N. Nikki Haley said in a statement, reported CBS News on its Twitter page. "We did not always see things the same way, but he unquestionably advocated his country's positions with great skill. We send our prayers and heartfelt condolences to lift up his family and the Russian people."
Former U.S. Ambassador to the U.N. Samantha Power expressed a similar sentiment, despite clashing with Churkin in the past.
"Devastated by passing of Russian UN Amb Vitaly Churkin," Power tweeted. "Diplomatic maestro &deeply caring man who did all he [could to bridge US-RUS differences."
A year earlier, Churkin came down hard on Power after she said Russia was partially responsible for the horrors that have occurred in Syria.
"The weirdest speech to me was the one by the U.S. representative who built her statement as if she is Mother Teresa herself," Churkin responded at the time, according to the BBC. "Please, remember which country you represent. Please, remember the track record of your country."