LVIV, Ukraine — Stanislav Shushkevich, who steered Belarus to independence, served as its first leader and is reported to have taught Russian to John F. Kennedy assassin Lee Harvey Oswald in the 1960s, has died. He was 87.

Shushkevich died early Wednesday, according to his wife, Irina, after hospitalization last month for COVID-19.

Shushkevich was a harsh critic of Belarusian President Alexander Lukashenko, who succeeded him as the nation's leader in 1994 and has ruled with an iron fist ever since, relentlessly crushing dissent.

When Russia invaded Ukraine on Feb. 24, Shushkevich criticized Lukashenko for allowing Moscow to use Belarus as a staging ground for amassing troops and launching the war.

"When the occupation of Belarus ends, when peace, the law and sovereignty return to Belarus, streets and monuments to Stanislav Shushkevich will certainly appear in Belarussian cities," Belarus' exiled opposition leader, Sviatlana Tsikhanouskaya, said Wednesday.

Memorializing Shushkevich, she said his "journey toward a free, peaceful and independent Belarus we're continuing, day by day."

Shushkevich, a university professor, became a lawmaker in Belarus during Soviet leader Mikhail Gorbachev's political reforms. Following a botched hardline Soviet coup in August 1991, he was elected to lead the then-republic as the speaker of the Belarusian legislature.

On Dec. 8, 1991, Shushkevich hosted the leaders of Russia and Ukraine at a secluded hunting lodge near Poland to sign an agreement that declared the Soviet Union defunct and formed a new alliance of the three Slavic republics called the Commonwealth of Independent States.

Two weeks later, eight other Soviet republics joined the alliance, effectively terminating the authority of Gorbachev, who stepped down on Dec. 25, 1991.

Shushkevich spoke about the signing of the agreement with pride in an interview last year with The Associated Press. He called the accord he signed with Boris Yeltsin of Russia and Leonid Kravchuk of Ukraine a "diplomatic masterpiece."

"A great empire, a nuclear superpower, split into independent countries that could cooperate with each other as closely as they wanted, and not a single drop of blood was shed," Shushkevich told the AP.

"We decided to shut the prison of nations," he said. "There was nothing to feel contrition for."

Shushkevich argued that he and the other leaders saw no point in Gorbachev's efforts to keep the remaining 12 Soviet republics together.

The Baltic republics of Latvia, Lithuania and Estonia already had seceded, and the failed August coup against Gorbachev by hard-line Communist Party members had eroded his authority and encouraged other republics to seek independence.

"All versions of the union treaty boiled down to the restoration of the old ways or to Gorbachev's proposal of a new structure where he still would be the boss," Shushkevich said.

As Belarus' first post-Soviet leader, Shushkevich faced daunting challenges amid an economic meltdown and political turmoil that followed the breakup of the USSR. Shushkevich's popularity waned, and when the country held its first presidential election in 1994, populist Lukashenko won by a landslide after promising to shore up the crumbling economy, combat corruption and restore Soviet-era social benefits.

Before his prominent role in the breakup of the USSR, Shushkevich became a footnote in another historic event. He taught Russian to Lee Harvey Oswald when they worked at the same radio factory in Minsk in the early 1960s. Oswald went on to assassinate U.S. President John F. Kennedy.

Lithuanian Prime Minister Ingrida Simonyte tweeted about the news of Shushkevich's death that "his signature on the declaration dissolving the Soviet Union will live in history, his memory - in our hearts."