Defence Minister Manohar Parrikar today said there is scope for improvement in security as some sort of lethargy has set in over a period of time and said those behind any lapse in Nagrota terror attack will have to pay for it. <br/><br/>Speaking at HT Leadership Summit in New Delhi, Mr Parrikar also said, the recent surgical strike was a good confidence building measure for India and it has led to a sense of uncertainty in the Pakistani security establishment.