Israel has killed one senior Iranian leader after another in airstrikes as it seeks to topple the Islamic Republic. But its past experience of targeting senior militants shows the strategy has limits and can sometimes backfire. Israel killed Hezbollah leader Hassan Nasrallah. The group still fires rockets. It took out Hamas' top brass. The group still controls half of Gaza and has not laid down arms. As a strategy, targeted killing has rarely been employed against a state. While it may provide tangible achievements that leaders can brand as victories - especially in wars with no clear endgame - it rarely addresses the underlying grievances that propel conflicts. Jon Alterman, chair of Global Security and Geostrategy at the Centre for Strategic and International Studies, said the impact of targeted killings often fades over time. He noted that Iran's government and military are made up of several overlapping institutions that have so far survived waves of punishing US and Israeli