Question

Which internal event signaled the end of the Soviet Union

Answer 1

Answer: The fall of the Berlin Wall a symbol of the "Cold War" divide of Europe was one of the nails in the coffin of the Soviet Union, which collapsed at the end of 1991.

Hope this helps :D

Answer 2

On August 18, 1991, concerned members of the Communist party in the military and government placed Gorbachev under house arrest.