Canada is on contract to pay something like $ 551 million in development costs toward the F 35 program . They ' ve paid something like $ 350 million of it so far . In return , they ' re allowed to bid on contracts to produce parts for the F 35 program . They ' ve won over $ 1 billion in contracts so far . If Canada announces the Super Hornet or any other plane as the eventual replacement for their CF 18 ' s , they ' d have to pony up the remaining $ 200 million , and be locked out of further contracts on the F 35 . So calling it an interim purchase is a smart move since they get to continue to win contracts on the F 35 , yet get started on a probable eventual replacement . They do have to pay the remaining $ 200 million anyway , but this means they can continue to win more production contracts in the meantime .