Complex sentence: Karmal's leadership was seen as a failure by the Soviet Union because of the rise of violence and crime under his leadership, he was replaced with Mohammad Najibullah who was able to cling to power until 1992 three years after the withdrawal of the Soviet army.
Split into simpler sentences: Karmal's leadership was seen as a failure by the Soviet Union because of the rise of violence and crime under his leadership. He was replaced with Mohammad Najibullah, who was able to cling to power until 1992, three years after the withdrawal of the Soviet army.