The coins / medals represent the level of cooperation that had begun between the USSR and the United States in those years. Each coin / medal represents issues of cooperation and freedom in the USSR.
1. Peace and Cooperation
2. INF Summit Treaty Medallion
3. Millennium of Christianity
4. Thousand Years of the Ruble

Warning: super large images!
Front Image
Back Image
Appearently, the INF amd the Christianity medals were presented to both President Reagan and General Secrarty Gorbachev.
The forth medal served a prototype of the first Soviet silver commemorative coin, which is used in the design of the 1,000 years of the mintage of Russian coins.
All these are considered pretty rare, considering all of them except the Peace and the Cooperation medal had a scarce mintage of 1,000 and the "polar bear" one had a mintage of just 10,000.
P.S. The Polar bear medal is one of those rare times when an American and a Soviet medallist designed this medal.
Hope you enjoyed it