Atrios is right, a cost-benefit analysis doesn't justify spying on allied leaders.
While any spying effort can unearth something useful, spying on countries that already openly cooperate and share information is less likely to produce useful things than spying on just about anyone else. Meanwhile, the cost to those relationships if the spying ever became known would be enormous. And given that thousands of people are involved in America's sprawling spy apparatus, many of whom work for contractors rather than directly for the government, it's become quite likely that any spying the U.S. does will eventually leak out. You can't keep that many people in the loop about a secret, without it coming out. And that's especially true when some of the people in the know are just subcontractors and aren't directly accountable to the spy agencies that are trying to keep this stuff secret.
The chances of big gains from spying on allies are low, the cost of the spying is discovered is high and the chances of that the spying will eventually be leaked out and discovered are also high. I suspect the reason this stuff happened is the NSA has a lot of nifty gizmos and the people using that technology realized they could, so they did. This wasn't some malicious campaign against the country's friends, it was some people geeking out with their high-tech toys without looking at the big picture.
While any spying effort can unearth something useful, spying on countries that already openly cooperate and share information is less likely to produce useful things than spying on just about anyone else. Meanwhile, the cost to those relationships if the spying ever became known would be enormous. And given that thousands of people are involved in America's sprawling spy apparatus, many of whom work for contractors rather than directly for the government, it's become quite likely that any spying the U.S. does will eventually leak out. You can't keep that many people in the loop about a secret, without it coming out. And that's especially true when some of the people in the know are just subcontractors and aren't directly accountable to the spy agencies that are trying to keep this stuff secret.
The chances of big gains from spying on allies are low, the cost of the spying is discovered is high and the chances of that the spying will eventually be leaked out and discovered are also high. I suspect the reason this stuff happened is the NSA has a lot of nifty gizmos and the people using that technology realized they could, so they did. This wasn't some malicious campaign against the country's friends, it was some people geeking out with their high-tech toys without looking at the big picture.
