It is the big question: Could more have been done to prevent the Mumbai massacre?

While terrorism experts say Indian special forces performed with remarkable bravery and professionalism in their battle with the terrorists, they believe the attacks should — and could — have been thwarted by better intelligence.

Professor Paul Wilkinson lectures in international relations at the University of St. Andrews and is joint editor of the academic journal Terrorism and Political Violence.

He told Sky News: "We have to accept there was an intelligence failure. They should have nipped this in the bud but it wasn't on their radar. Intelligence doesn't come out of this very well. This was a major operation with lots of people involved. It wasn't just a cell; there were teams of gunmen — lots of well trained people. A large number of people must have been in the know about this attack."

Former SAS trooper Robin Horsfall, who took part in the storming of the Iranian embassy in 1980, also believes the international intelligence community should have known the attacks were being planned.

"The security services weren't sure what they were dealing with and it was very difficult for them. A lot of things will no doubt come out after it's all over about what happened and why. The real failure though was in the intelligence. The whole world is trying to stop these things — this was a failure in terms of the intelligence but a success in terms of security in general."

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