The Canadian government said today it will spend $8.5 billion to purchase a new wave of fighter jets from U.S. aerospace giant Lockheed Martin. The deal to purchase 65 F-35 Lightning II Joint Strike Fighter jets marks one of the biggest military equipment purchases in the country's history, AP cited Defense Minister Peter MacKay as saying. MacKay said the new jets would replace the Air Force's aging fleet of CF-18s that recently underwent a $2.4 billion upgrade. The contract is worth $8.5 billion, but the full cost could rise to as much $17 billion once the government signs a maintenance contract. The Defense Department said the Joint Strike Fighter program is the single largest fighter aircraft program in history, funded by the United States, Canada, Turkey, Britain, Italy, Norway, Denmark, Australia and the Netherlands. The total value of the program is expected to exceed $383 billion, with production expected to top 5,000 aircraft. Canada has invested $151 million so far to develop the F-35, and Canadian companies have received $332 million in contracts, according to military reports. McKay said the deal will ensure Canada remains interoperable with its major allies.