The Islamist group "was a massive movement for young people going to the mosques in the poverty of the refugee camp", Yaari says, and it would later take on a similar importance for Hamas.
(snip)
Yaari says he was responsible for numerous "brutal killings" of people suspected of co-operation with Israel. "Some of them with his own hands and he was proud of that, talking about it to me and to others."
(snip)
Sinwar has spent a large part of his adult life - over 22 years - in Israeli prisons, from 1988 to 2011. His time there, some of it in solitary confinement, appears to have radicalised him even further.
(snip)
Non-state organisations tend to operate like a hydra's head - one operational commander or figurehead leader gets removed and they are quickly replaced by another. Their successor sometimes lacks the same experience or credibility but the organisation still manages to regenerate itself in some form.