By the end of 1948, the Soviet bloc was perceived as a serious threat to security in Europe. The Cold War had begun and peacetime activities were no longer a priority for the air force. The Canadian government began preparing to meet this threat. In December 1948 the government decided to increase the number of RCAF establishments, increase the size of and recondition existing air stations, recruit additional personnel, and obtain and produce new (jet) aircraft. Although the RCAF had a jet fighter in 1948, the British de Havilland Vampire, it would be replaced, beginning in 1951 by the more effective Sabre, built under licence by Canadair. The new Avro CF-100 "Canuck" was also built and entered squadron service in April 1953. The RCAF was the first air force to operate jet transportation aircraft with two Comets entering service in 1953. Re-equipping and expansion of the air force led to the government abandoning its plans for just eight squadrons.