Worth a read and the sub-title:
Head of Mossad who restored its reputation for daring and used terror tactics on Israel's enemies
Link:http://www.telegraph.co.uk/news/obit...-obituary.html

This photo explains much of his motivation
A famous photograph shows his grandfather on his knees before Nazi soldiers shortly before he was killed. Mr Dagan kept the photograph in his office and would show it to foreign visitors as an explanation of his devotion to Israel's security.
Link:http://www.telegraph.co.uk/news/worl...eir-Dagan.html