 In December, CA$27 million was provided to start flight modelling.At first, the project was limited in scope, but the introduction of the Soviet Myasishchev M-4 "Bison" jet bomber and the Soviet Union's testing of a hydrogen bomb the next month dramatically changed Cold War priorities.In March 1955, the contract was upgraded to CA$260 million for five "Arrow Mk.1" flight-test aircraft, to be followed by 35 "Arrow Mk.