Final answer:
Gorbachev's reforms, economic challenges, and independence movements contributed to the collapse of the Soviet Union, coupled with Eastern European grassroots efforts that played a significant role.
Step-by-step explanation:
Supporting Details about the Collapse of the Soviet Union
One significant supporting detail about the collapse of the Soviet Union is the series of reforms initiated by Mikhail Gorbachev. Gorbachev's policies of perestroika (restructuring) and glasnost (openness) were intended to revitalize the Soviet system but ultimately contributed to its downfall. Economic struggles, the pressure of maintaining control over satellite states, a costly war in Afghanistan, and the rise of independence movements within the Soviet Union itself also played critical roles. Communist hard-liners opposed to Gorbachev’s reforms attempted a coup in August 1991, which failed but signaled the USSR's instability. By December 1991, the Soviet Union officially disbanded, with republics such as Estonia, Latvia, and Lithuania declaring independence.
In the broader context, the fall of the Soviet Union was also influenced by the actions of the people in Eastern Europe. While the US and its Cold War strategies played a part, the role of Eastern European citizens in initiating grassroots efforts to push for democracy and independence cannot be overlooked. These events cumulatively demonstrate that the collapse of the Soviet Union was the result of a complex set of internal challenges and external pressures along with the significant impact of individual and collective actions of those both inside the Soviet Union and in its sphere of influence.