Assassination vs War

Saddam Hussein the day of his capture

Saddam Hussein the day of his capture

How is it that we (civilized society) consider it less immoral to go to war and in the process murder/kill/maim/dispossess hundreds of thousands than to kill one man and his family of butchers?

This I do not understand and likely never will.

US Policy on Assassinations (CNN)

History of US Targeted Killings (Assassination) Policy