The Kremlin could have started World War III in 1989 had it used troops to crush the demonstrations that preceded the fall of the Berlin Wall, former Soviet leader Mikhail Gorbachev said.

Gorbachev is hailed in the West for ignoring hardliners who advised him to guarantee the Soviet Union’s future by crushing a growing wave of dissent in Eastern Bloc countries that led to the fall of the Berlin Wall on Nov. 9, 1989.

When asked by a reporter why he did not use force to halt the demonstrations, Gorbachev said Tuesday that it would have sparked a catastrophic set of events and even a world war.

“If the Soviet Union had wished, there would have been nothing of the sort [the fall of the wall] and no German unification. But what would have happened? A catastrophe or World War III,” said Gorbachev, 78.

“My policy was open and sincere, a policy aimed at using democracy and not spilling blood. But this cost me very dear, I can tell you that,” he said.

Thousands of East Germans crossed to West Berlin in November 1989 after the Soviet-backed authorities unexpectedly ordered the opening of tightly guarded border crossings in the wall.

Gorbachev, who could have used nearly half a million Soviet troops stationed in East Germany to crush the rebellion, quipped that he had “a good night’s sleep” after the wall was opened.

“I am very proud of the decision we made,” he said. “The wall did not simply fall — it was destroyed just as the Soviet Union was destroyed.”

The fall of the Berlin Wall — a symbol of the Cold War divide of Europe — was one of the nails in the coffin of the Soviet Union, which collapsed at the end of 1991.

After becoming Soviet leader in 1985, Gorbachev — then 54 — battled against the conservative wing of the Communist Party to push through reforms that dismantled the one-party system, freed the press and ended restrictions on religion.

The father of glasnost and perestroika said he had not wished to preside over the Soviet collapse, adding that it was destroyed by internal discord.

The Soviet collapse also signaled the end of Gorbachev’s own political career. Despite winning the Nobel Peace Prize in 1990, he never won elected office afterward and nowadays appears much more often abroad than in Russia.

But Gorbachev warned that the West had also made mistakes, missing an opportunity to build lasting peace in Europe by being over-triumphant after the Soviet collapse.

“The West and above all the United States thought that they had a full monopoly in their hands. … Their triumphalist complex cost a fair amount: a lot could have been resolved and wars avoided in Europe,” he said.

“They now need their own perestroika,” he said, adding that he was glad Barack Obama had won the U.S. presidential election.

“The lesson from the Berlin Wall is not to divide up the world again. We must live peacefully in the European house together with all its windows and doors,” Gorbachev said.