Pakistan, Pakistan, Pakistan. We know they HAVE BEEN the training Hq. The question is: Is it continuing?
With a population of about 140 million, over 95% Muslim, they can easily operate. In fact isn't the latest idea, that bin Laden is somewhere there (if still alive)?
As the Indian Foriegn Minster stated, Pakistan IS the epicenter of international terrorism. It will take a long drawn-out effort, if not a fight, to change that!