Two useful articles today. Their focus is on the USA, although a number of aspects have a wider application.

A long piece in The New Yorker, with a title and sub-title:
The Whole Haystack; The N.S.A. claims it needs access to all our phone records. But is that the best way to catch a terrorist?
Link:http://www.newyorker.com/magazine/20...whole-haystack

taken from the opening passages:
Almost every major terrorist attack on Western soil in the past fifteen years has been committed by people who were already known to law enforcement....In each of these cases, the authorities were not wanting for data. What they failed to do was appreciate the significance of the data they already had.... He cited a statement by Alexander’s deputy that “there’s only really one example of a case where, but for the use of Section 215 bulk phone-records collection, terrorist activity was stopped.” “He’s right,” Alexander said.
The second FP essay has the title:
The Myth of the Terrorist Safe Haven; A pernicious and persistent theory that America’s enemies flourish in foreign sanctuaries -- and that only military means can rout them -- has led us abroad in search of monsters to destroy.
Link:http://foreignpolicy.com/2015/01/26/...st-safe-haven/

A taster from the penultimate paragraph:
..evidence of the true threat of terrorism to Americans suggests that a hotel room in Hoboken can be just as much a safe haven as a hut in Helmand — and more dangerous too, given the proximity to American targets.