Original sentence: The war began when Iraq invaded Iran on 22 September 1980 following a long history of border disputes, demands for the overthrow of Saddam Hussein's regime, which was embroiled in a dispute with the new Islamic Republic of Iran
Edited sentence: The war began when Iraq invaded Iran on 22 September 1980 following a long history of border disputes, demands for the overthrow of Saddam Hussein's regime, and secret encouragement by the US administration (President Jimmy Carter, conveyed through Saudi Arabia) which was embroiled in a dispute with the new Islamic Republic of Iran