Describe one U.S. policy and one soviet policy that contributed to the fall of the Soviet Union and European communism in the early 1990s. What type of impact did the two policies have? Why?
The economic system of Soviet Communism was not sustainable; the question was not if it would fail but how and when. By trying to coerce people into working instead of giving them the incentive of working for higher incomes, the USSR handicapped its own economic productivity substantially.
But there were definitely policy decisions along the way that triggered the final collapse.
One US policy that was very important was a huge surge in US military spending under Ronald Reagan. Rumor has it that this was actually an accident, the result of clerical errors combined with the high inflation of the time. Whether or not that's actually true, the reality clearly was that the US enormously increased military spending in the 1980s, and in fact increased it so high that due to US economic superiority there was simply no way the USSR could possibly have matched US military production even if they spent literally everything they had on the military.
Partly as a result of being so obviously outmatched, but also in an effort to pull back from the conflict that the Soviet Union was obviously losing ground in and modernize the Soviet economy, Gorbachev restructured Soviet military policy, called perestroika ("restructuring") and glasnost ("transparency"). He downsized the Soviet military and pulled out troops from a number of countries in Eastern Europe.
But Eastern European countries could see that the capitalist (or, more properly, mixed-capitalist social democracy) system in Western Europe was leading to much greater prosperity and freedom than the Communist system they were under. Without Soviet troops holding them to the Communist system, a number of Eastern European countries began to defect from the Soviet Union and begin reforms to be more like Western Europe. Shortly thereafter, other countries left the Soviet Union, and in a few years the whole USSR had fractured apart.