A real tragedy, my condolences to all those affected.
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Regarding who to blame, Pakistan is always such an easy target. Blaming Pakistan is to actually say that the Pakistan Gov, military planned and help carry out this act. You would of course need some proof for this accusation. There have been many terrorist attacks in Pakistan itself recently, most notably the bombing of the Marriot Hotel in Islamabad, people seem to forget these incidents very quickly.
The attack was well planned and from what I've read weapons and explosives were probably stockpiled in those hotels and other places. And experts have said there must have been support from within the Indian security forces. It was an outrageous attack, there are many questions that need answering and to blame it all on Pakistan is not only nonsensical it is very unhelpful.