Certainly not the CIA. Over the last decade or so they missed amongst others: The Indian and Pakistan nuclear bomb tests. The bombings of the WTC (the first time around.) 9/11. USS Cole. Embassy bombings in Africa. "Torture memos," etc etc. So what country has the best foreign intelligence service and why? I nominate Pakistan's ISI for the simple reason that they have kept the West on a short leash for more than ten years but still we are not within ten light years of figuring them out.