If Russia spent as much on intelligence agencies as the United States does - $52.6 billion in 2013, according to the "black budget" published by the Washington Post last August - would it have been able to stop the suicide bombers who killed 31 people in two attacks in Volgograd
Time to question figures around national security
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There was one exception, 12 years ago, when foreign terrorists did manage to get into the United States and carry out an attack. However, the 9/11 attackers were using a brand new technique. Such innovations are very rare, and are only a surprise the first time. No subsequent terrorist attack, in the US or anywhere else, has been remotely as ambitious.
The NSA has certainly not prevented 10 9/11s in the past decade; it's very unlikely to have prevented even one. But let us accept, for the sake of the argument, that the NSA's activities have really saved 759 American lives in the past decade. In fact, let's round it up to 1000 lives, to make the calculations easier.
That would mean over the past decade, the NSA has spent about US$100 billion to save 1000 American lives. That works out at $100 million per life saved.
Economists talk about "opportunity cost": when you spend the money on one thing, you are forgoing whatever benefits you might have got from spending it on something else. Are there other ways of spending that $100 billion that would save more than a thousand American lives?
Consider spending some of it on better pre- and post-natal care for poor Americans. Just a billion dollars a year - an extra $250 per baby - would enable the US to get its infant mortality rate down below Cuba's, maybe even as low as Portugal or South Korea. Over 10 years, that would be 60,000 more American kids who lived to grow up.
Or take highways. Highway engineers can estimate how many people will die each year on a given stretch of highway fairly accurately. It depends on the width and surface of the road, how many sharp curves and blind hills there are, whether there are guard rails, etc. All those things depend on how much money you spend on that stretch of highway.
Around 34,000 Americans died on the roads in 2012. A further $5 billion a year, spent on making highways safer, would probably reduce that toll by an extra thousand people each year. Over 10 years, it would save around a further 60,000 lives.
That's 120,000 lives saved, and there's still $4 billion a year left to spend on other life-saving improvements. You almost certainly end up saving at least 150,000 American lives with your $100 billion investment. That's at least 150 times better than your return on investing the money in the NSA - and we haven't even considered the cost in alienated allies and violated civil rights of giving the NSA that money.
Unfortunately, Americans dying in infancy or on the highways don't make headlines, whereas victims of terrorism do. Politically, their lives are much more important, and so that's where the money goes.
Indeed, even making calculations of this sort about the relative value we assign to human lives is thought to be in poor taste.
Never mind. As Herman Kahn said when people criticised him for making cold-blooded estimates of how many millions of Americans would be killed as a result of various different US strategies for fighting a nuclear war: "Would you prefer a nice, warm mistake?"
Gwynne Dyer is an independent journalist whose articles are published in 45 countries.