Original sentence: MacArthur sought an extension of the conflict into China, but President Truman stubbornly refused his request (regarded by some as a wise decision: extending the war to China might have required nuclear strikes, which could have brought Chinese ally the USSR into the war and perhaps launched a Third World War)
Edited sentence: MacArthur sought an extension of the conflict into China, but President Truman stubbornly refused his request (often regarded as a wise decision: extending the war to China might have required nuclear strikes, which could have brought Chinese ally the USSR into the war and perhaps launched a Third World War)