I grew up during the Cold War when the enemy was the Warsaw Pact; the Soviet Union and her allies. They were somebody to be anxious about. Three million men under arms, 36,000 tanks and 15,000 nuclear weapons. If the Warsaw Pact had wanted to attack New York it would have been with a five megaton nuclear weapon delivered by missile from somewhere in Siberia. They would not have needed to hijack aircraft to crash into skyscrapers. At any time during the Cold War we could have had a thermonuclear war which could have killed hundreds of millions of people. We came very close to it during the Cuban missile crisis. There were also at least two times when we came close to starting a war by accident. The world has been a far safer place since the Cold War ended. The threat caused by terrorism does not compare with the threat posed by a nuclear armed superpower.
The risk posed by Al-Qa'eda has been grossly exaggerated for political ends. To divert attention from other events and justify infringements of civil liberties. Though the Warsaw Pact posed a far greater threat than any terrorist organisation can ever do we never found it necessary to sacrifice privacy and liberties in the way we are doing now. Terrorism is a threat, but it is only one of many that face us. It is certainly not the most serious one. Global warming, globalisation, the possibility of global pandemics and the rise of China as a world power are all potentially more serious threats to our security.