Identify the border dispute that is most closely related to the breakup of the Soviet Union.

The border dispute that is most closely related to the breakup of the Soviet Union is the Nagorno-Karabakh conflict.

The border dispute that is most closely related to the breakup of the Soviet Union is the Nagorno-Karabakh conflict between Armenia and Azerbaijan.

The border dispute that is most closely related to the breakup of the Soviet Union is the Nagorno-Karabakh conflict. To understand this, let's go step by step on how to arrive at this answer:

1. Start by considering the breakup of the Soviet Union: The Soviet Union dissolved in 1991, leading to the independence of several states that were previously part of the Soviet Union.

2. Next, focus on the border disputes that emerged as a result of this breakup: The dissolution of the Soviet Union resulted in the emergence of several border disputes among these newly independent states. These disputes were primarily over territories with significant ethnic or historical significance.

3. Consider the region and the conflict involved: Nagorno-Karabakh is a region located in the South Caucasus, between Armenia and Azerbaijan. It is primarily inhabited by ethnic Armenians, but it was assigned to the Azerbaijan Soviet Socialist Republic by the Soviet authorities.

4. Analyze the connections between the conflict and the breakup of the Soviet Union: The Nagorno-Karabakh conflict is closely related to the breakup of the Soviet Union because the dissolution of the USSR led to a power vacuum and a resurgence of nationalism in the region. As the Soviet Union collapsed, tensions between Armenia and Azerbaijan escalated, leading to a full-scale war between 1991 and 1994 over the control of Nagorno-Karabakh.

5. Justify the selection: The Nagorno-Karabakh conflict stands out as the most closely related border dispute to the breakup of the Soviet Union due to its timing, geographical location, and ethnic dynamics. It represents a case where the power vacuum created by the Soviet Union's dissolution directly fueled a violent conflict that continues to this day.

So, the answer is the Nagorno-Karabakh conflict.