Who was Ismail Haniyeh, the Hamas political leader who was killed in Iran?

His addition on that list would allow the U.S. government to block his assets under a Bush administration executive order. "Ismail Haniyeh is the leader and President of the Political Bureau of Hamas. Haniyeh has close links with Hamas's military wing and has been a proponent of armed struggle, including against civilians," the U.S. Bureau of Counterterrorism and Countering Violent Extremism said in a 2018 report.