Hi mate....what are you trying to compare? Nuclear deterence based on cold war thinking versus the 9/11 attack or just the number of weapons during the 60s versus the number of weapons in the ought 20s?
If its numbers of weapons then yes the US has 10% of what it had during the height of the cold war but the significance is no less - its just the the threat has changed.
If you're just looking at 9/11 and terrorism well I guess the hi-jacking is a function of airline security, internal and overseas intelligence and law and order failures ?
You've brough a lot to the table mate!