WASHINGTON -- Three former top Soviet officials on Friday marked the signing 25 years ago of the treaty that formally dissolved the Soviet Union, and they used the occasion to urge dialogue on the deadly separatist conflict in Ukraine.

On Dec. 8, 1991, the leaders of the Soviet republics of Russia, Ukraine and Belarus signed a pact that broke up the U.S.S.R. Negotiations were held in secret in a government hunting lodge in Belarus, and the pact defeated the efforts of Soviet leader Mikhail Gorbachev to keep the country together.

One of the signatories, Stanislav Shushkevich, then head of the Belarusian parliament, said the deal helped avoid civil wars and other calamities that could have resulted from the break-up of the world's largest country and one with a huge arsenal of nuclear weapons.

"There was a nuclear power which was threatening the entire world with nuclear missiles and to say that it will cease to exist, one must be not just a philosopher, but a philosopher with a touch of heroism," Shushkevich said at an event at the Atlantic Council think-tank in Washington.

Gennady Burbulis, a close aide of the late Russian President Boris Yeltsin, who signed the document together with his boss, said the Soviet Union was a doomed totalitarian state.

"Historically speaking ... the Soviet Union was an inviable entity from the get-go," Burbulis said. "The repressions of the system were an anthropological catastrophe."

But while the Belovezha agreements, as they became known, led to the peaceful creation of 15 independent post-Soviet states, a number of ethnic conflicts and territorial disputes took place in the region, causing wars and devastation. And even though the dissolution of the Soviet Union gave hope to liberalization, only a few post-Soviet countries have emerged as true democracies.

"A whole range of symbols of the old Soviet Union have been resurrected because the mentality of Soviet people has been preserved," Shushkevich told reporters before the event.

Twenty-five years later, the region is again in turmoil. In 2014, after protesters toppled a pro-Russian government in Ukraine, Russia annexed the Crimean Peninsula and threw its support behind separatist rebels in eastern Ukraine. Some 10,000 people have been killed.

The United States and European Union have imposed economic sanctions on Russia in bid to pressure Moscow to stop supporting the separatists. Russia denies interfering in Ukraine.

International negotiations to enforce a peace deal have all but reached a dead end.

Former Ukrainian President Leonid Kravchuk, who also signed the Belovezha agreement, said it was important to continue talks, while also exerting economic pressure on Russia.

"My position is the same as of those countries that imposed the sanctions," Kravchuk said. "At the same time, I agree that you will not achieve order in the world only through sanctions."

But Burbulis, who served in Yeltsin's government, said Western sanctions and a harsh line against Moscow are ineffective. He called for a softer, more nuanced dialogue with the Kremlin.

"There is no other way than consensus, but consensus implies a different understanding of politics, a different culture of relations, not guided by the principle, 'I am stronger and you are poorer."'

Two and half decades later, the signatories of the treaty remembered the events differently and traded lively and often emotional remarks. Who takes credit for preparing the treaty? Who invited whom? Which leader got the first call warning that the treaty was about to be signed: Gorbachev or U.S. President George H. W. Bush? But the most heated exchange was over a different matter: Which of the signatories went hunting during the retreat?