Pretty difficult to determine which intelligence service is best. The Israelis, for example, have a pretty narrow focus that's limited to their immediate region. Their operations may be extend across the world; however, their operational focus is pretty limited. The US, on the other hand, has a much more global interest to the point where the political situation in Sierra Leone may have some impact on US foreign policy. The Israelis, on the other hand, couldn't care less what happens in Sierra Leone. This means that the US has to be more flexible, adaptable and responsive to changing situations worldwide.
Intelligence collection falls somewhere between projecting statistical probabilities and reading tea leaves. In other words, the riskier the target, the higher chance of failure. The US takes high risks whereas other nations stick to statistical probabilities. It's like judging the difference between a coach who always kicks on fourth down and one who is willing to go for it.
Then there's the political factor. Intelligence is basically an interpretation of certain events. However, it can't compete against other agendas. If we knew with absolute certainty, for example, that Canada was sponsoring terrorists attacks against US embassies in Africa, for instance, we wouldn't be able to launch a pre-emptive strike without suffering international political repercussions. We would have to wait until there was absolute evidence that could be presented publicly, and even then, I seriously doubt we would take any action.
