On Tuesday, Russian news media reported that Mikhail Gorbachev, the last leader of the Soviet Union, died at the age of 91 in Moscow.

"Mikhail Sergeyevich Gorbachev died this evening after a serious and long illness," the Central Clinical Hospital in Moscow announced, as Interfax, TASS, and RIA Novosti reported.

Gorbachev, who was in power from 1985 to 1991 and helped defrost US-Soviet ties, was the final Cold War leader still alive.

He spent most of the last two decades on the political periphery, sporadically appealing to the Kremlin and the White House to restore ties as tensions reached Cold War levels following Russia's annexation of Crimea in 2014 and offensive in Ukraine this year.

His relationship with Russian President Vladimir Putin was at times strained, but Putin expressed his "deep sympathies" upon Gorbachev's passing.

"In the morning [Putin] will send a telegram of condolences to his family and friends," Kremlin spokesman Dmitry Peskov told Russian news media.

As a precaution against the coronavirus, Gorbachev observed self-quarantine throughout the pandemic and spent his twilight years in and out of hospitals with progressively weak health.

In the West, where he was affectionately known as Gorby, Gorbachev was admired for defusing US-Soviet nuclear tensions throughout the 1980s and bringing Eastern Europe out from behind the Iron Curtain.

In 1990, he was awarded the Nobel Peace Prize for negotiating a historic nuclear armaments deal with US President Ronald Reagan. His decision to restrain the Soviet army when the Berlin Wall fell the previous year was crucial to preserving Cold War peace.

He was also lauded in the West for pushing measures to increase transparency and public discourse, which accelerated the fall of the Soviet Union.

After the news of his death surfaced, European Union Commissioner Ursula von der Leyen lauded Gorbachev as a "trusted and respected leader."

"He was instrumental in ending the Cold War and bringing down the Iron Curtain. It paved the path for Europe's liberation. This is a legacy we will never forget "she stated on Twitter.

Strained ties with Putin

On his 90th birthday, he was congratulated by world leaders, including US President Joe Biden and former German chancellor Angela Merkel. He was the first Russian leader to live over the age of 90.

Gorbachev remained controversial at home and had a tense rapport with Putin.

Putin and many Russians viewed the dissolution of the Soviet Union as a tragedy, resulting in a decade of widespread poverty and a decline in Russia's international standing.

Putin relies on the successes of the Soviet era to bolster Russia's claim to grandeur and its status, as many Russians still cherish the Soviet era.

As the Soviet Union fell, Gorbachev was replaced by Boris Yeltsin, who became the first president of post-Soviet Russia.

Gorbachev was, after that, forced to the sidelines, devoting his time to educational and philanthropic endeavors.

He made a dismal attempt to return to politics in 1996 when he stood for president but won only 0.5% of the vote.

Putin reversed many of his significant accomplishments over the years.

As an early backer of Russia's leading independent newspaper Novaya Gazeta, created in 1993, he gave a portion of his Nobel Prize money to assist the publication in purchasing its first computers.

During Putin's two-decade tenure, however, the newspaper and all independent Russian media were subjected to increasing pressure.