The killing of Hamas political leader Ismail Haniyeh in an air strike in Tehran on Wednesday blamed on Israel has stunned the international community. Haniyeh had been in Tehran to attend the inauguration of President Masoud Pezeshkian and Iran's supreme leader Ayatollah Ali Khamenei vowed "harsh punishment" for Israel. Palestinian Authority president Mahmud Abbas is a rival of Haniyeh but slammed the killing as "a cowardly act and a serious escalation," his office said in a statement. "He urged our people and their forces to unite, remain patient, and stand firm against the Israeli occupation."