When fellow British Columbian and ally Kim Campbell became PC leader and prime minister in 1993, Siddon was promoted to the senior cabinet, becoming Minister of National Defence on June 25, 1993. In this role, he was responsible for ordering new EH-101 navy helicopters to replace the aging Sea King helicopters. The deal was finalized, but the opposition Liberal Party of Canada made it an election issue and argued that the helicopters were too expensive. After winning the election, the Liberals cancelled the contract and incurred cancellation fees of $500 million (CAD). The Sea Kings have since had numerous crashes and require 30 hours of maintenance for every hour of flight time.