Mikhail Gorbachev has urged Russia and the United States to hold a summit over the crisis in Ukraine to prevent a potential catastrophe.
The former Soviet leader warned that the current disagreement between Russia and the West could have dire repercussions if the two sides do not reach a consensus.
"This is extremely dangerous, with tensions as high they are now. We may not live through these days: someone could lose their nerve," he wrote in a comment piece for Russian state newspaper Rossiyskaya Gazeta.
"I suggest the leaders of Russia and the United States think about holding a summit with a broad agenda, without preliminary conditions," he wrote.
"One needn't be afraid of 'losing face,' that someone will gain a propaganda victory: this should all belong to the past. One needs to think about the future".
Diplomatic ties between Russia and the West this year reached their lowest level since the end of the Cold War after Russia annexed the peninsula of Crimea from Ukraine in March.
The US and its allies responded to the move by imposing economic sanctions on Moscow. Western powers have imposed increasingly tough sanctions as the conflict in eastern Ukraine has escalated, accusing Russia of providing monetary and logistical backing to the pro-Russian rebels that have seized territory from Kiev.
Russia has denied providing the rebels with military assistance and defended its annexation of Crimea by saying its people voted to be part of Russia in a disputed referendum.