Final answer:
The collapse of the Soviet Union was caused by calls for independence from Eastern bloc nations, weakened military, and economic difficulties.
Step-by-step explanation:
The collapse of the Soviet Union was primarily caused by calls for independence from Eastern bloc nations, which led to the disintegration of the Soviet Union. These nations, such as Lithuania, Latvia, and Estonia, sought to break away from Soviet control and establish their own independent states. This process of independence movements is often referred to as the 'Singing Revolution'. The weakened Soviet military and economic difficulties also contributed to the collapse.
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