It seems there has never been a leader of Hamas better known to Israel than Yahya Sinwar, who was chosen this week in an internal process to succeed Ismail Haniyeh as the head of the political wing of the organization in the Gaza Strip. And vice versa: Sinwar spent 22 years in an Israeli prison and was released in the Gilad Shalit prisoner exchange deal in the fall of 2011. He speaks Hebrew, is familiar with the ways of Israeli society and knows everything about the Israeli mentality, abilities and sensitivities.

Since Sinwar was chosen, an interview he gave in 2006 to journalist Yoram Binor, in fluent Hebrew, has circulated online: In the interview he said, among other things, “We understand that Israel is sitting on 200 nuclear missiles. … We don’t have the ability to disarm Israel.” 

A decade ago, Sinwar suffered severe pain in his head, which made him panic. It was Israel that saved his life. He was diagnosed with a brain tumor and recovered after emergency surgery at an Israeli hospital. On Feb. 14, an Israeli prison service officer said that at that time Sinwar was panicked, feared for his life and was grateful for the quick and professional medical care he received.

This appreciation has dissipated over the years. Israel views Sinwar as one of the most extreme leaders in the history of Hamas, and many senior Israeli officials fear that his election to head the political arm in Gaza will make Hamas more extreme and contribute to a hastening of the next cycle of violence between Israel and the Gaza Strip.