 Although it was in the immediate interest of both Israel and Iran that Bull discontinue his co-operation with Saddam Hussein, he had worked for many different parties in many critical defence projects, and had become both an asset and a liability for several powerful groups simultaneously.Due to Bull's past ventures, it has been speculated that besides Iran or Israel, the CIA, MI6, or the Chilean, Syrian, Iraqi, or South African government could have been behind his assassination.Project Babylon was stopped when supergun parts were seized by Customs in the United Kingdom in November 1990, and most of Bull's staff returned to Canada.