WASHINGTON — It seems obvious: Killing terrorist leaders should weaken their organizations, depriving those groups of strategic direction and ideological appeal. The death of someone like Abu Muhammad al-Adnani, a senior Islamic State figure reported killed on Tuesday in Syria, should seem like a significant setback for the group.

But scholars have struggled to find evidence that killing leaders is an effective way to dismantle terrorist organizations, instead finding ample evidence that it makes little difference. That research seems to apply especially to the Islamic State, also known as ISIS or ISIL, whose attributes make it resilient to losing even a top figure like Mr. Adnani.

Two features make a terrorist group able to withstand a senior officer’s death, according to research by Jenna Jordan, a Georgia Tech professor and a leading expert on the subject.

The first is popular support. Groups need a steady stream of recruits and a pool of potential new leaders. Support among civilians in areas in which the groups primarily operate also makes them more stable, by broadening support networks and helping them to safely retrench when needed. Leaders are usually killed in or near communities that support them, resulting in those communities rallying behind the terrorist group and against whoever did the killing.