What have we learned about fighting terrorism since 9/11? 

During the Global War on Terror, I often found myself working for either those who relished bringing death to our adversaries or those who struggled to give the command, “release weapons.” Both executed the same “leadership decapitation” strategy the United States still follows, aimed at disrupting or dismantling terrorist organizations by targeting their top leaders for capture or elimination.  

There is no consensus among the scholarly examinations as to whether leadership decapitation works. Jenna Jordan’s comprehensive 2019 study concluded that, over the long run, leadership decapitation “has been largely ineffective.” Yet Jordan acknowledged how the lack of agreement on which measures and criteria to include for analysis allows for “a large variation in the conclusions.”

Israel continues to lean into this strategy against Hamas, Lebanese Hezbollah and Iran, as it has for decades. It’s hard to say Israel is safer today, as the world waits to learn whether an all-out regional war will follow Tel Aviv’s presumed responsibility in assassinating Hamas political leader Ismail Haniyeh last month in Tehran.  

The aftermath of the Oct. 7 attacks in Israel is much like I remember the aftermath of 9/11 in the U.S. The mood was one of desperation, dread and a passion for vengeance. There was little appetite then, or now, for the long game. 

After 9/11, the U.S. took years to refine the art and science of “find, fix and finish” and build the tools to deliver what the government refers to as “lawfully, legal targeted killing.” I observed first-hand the transition in U.S. counterterrorism methodology from capture operations to selective kinetic targeting of high-value targets and thereafter a high-intensity, volume-driven killing campaign.

Leadership decapitation champions marveled at the capability, the metrics and the perceived tangible impact. Viewers observed dazzling displays of subsonic missiles that could surgically eliminate a single man through a window while sparing others in an adjoining room. A slight shake of the camera as missiles left the rails and a flash would be followed by a fireball incinerating an individual on foot, riding a motorcycle or under a tree, all without harming nearby civilians owing to the absence of explosives.  

The U.S. became extraordinarily adept at manhunting and killing.  

The reasoned argument held that although targeted killing might not destroy these groups or extinguish their threats, it didn’t have to. Rather, we could degrade them to near dormancy, achieving “strategic defeat.” Doing so, however, required a constant, high-intensity campaign, producing the popular buzzwords, “sustained counterterrorism pressure.” 

Others, myself included, looked at the landscape long-term and from 360 degrees. The capability is an invaluable tool, but just one in a necessarily holistic approach. Its overuse could bring diminishing returns and wreak dangerous, generational consequences akin to those stempping from our support of the Mujahideen against the Soviets in Afghanistan.  

Destroying rather than degrading terrorist organizations meant changing the conditions facilitating the recruitment, messaging, financing, logistics and training on which terrorist groups depended. Success required insight into terrorist plans and capabilities, informing a more balanced combination of selective kinetic strikes and capture operations, the latter largely done in cooperation with foreign partners. Detainees yielded significant intelligence and source acquisition opportunities. Such hard power also needed complementary counter-messaging, covert influence and constructive public policy.  

Renowned counterterrorist expert Colin Clarke, in reviewing the 2019 Jordan study, hits on one of the reasons leadership decapitation won out. "Another problem with decapitation strikes,” Clarke writes, “is the issue of ‘intel gain-loss,’ or the decision over whether the value of collecting information from an enemy target is more worthwhile than destroying the target itself.” What Clarke couldn’t know was the political risk officials feared. They could lose the target, or the group might conduct an attack while he sat in our crosshairs. Either outcome would surely end a once promising career.

From my experience, leadership decapitation yielded short-term tactical gains but long-term complications. The U.S. killed hundreds of bona fide terrorist leaders during my era across al Qaeda, its Sunni extremist partner groups, and the Islamic State. Their removal often disrupted attacks because the dead took their plans and personal relationships with them to the grave, and their successors routinely lacked the same experience, gravitas and networks. Terrorist organizations could replace personnel, but they were forced on the defensive.

However, leadership decapitation also taught terrorist groups to become more resilient and decentralized to ensure survivability. Their threats metastasized globally through loosely connected, self-sufficient and largely autonomous affiliates. Splinter groups like Abu Musab al-Zarqawi’s in Iraq and Abu Bakr al-Baghdadi’s Islamic State were more dispersed, and arguably more violent, indiscriminate and unpredictable. Seeding chaos and fear by inspiring indigenous lone wolves rather than directing external operatives became a low-cost, high-impact and decidedly difficult tactic to stop.   

U.S. officials are blunt about today’s heightened threat from foreign and domestic terrorism. In June, former CIA Deputy Director Michael Morell and Graham Allison, the former assistant secretary of Defense for policy and plans, published “The Terrorism Warning Lights Are Blinking Red Again.” They express grave concern and caution that such public pronouncements are driven by classified intelligence and should be heeded.  

For those who argue that leadership decapitation has made us safer, I wonder if their sentiments aren’t perhaps influenced by how desensitized Americans have become to the now normalized changes to our daily lives required to defend against terrorism. But as I’m reminded every time I go to an airport or attend a public event, as Taylor Swift fans are now painfully aware, it sure doesn’t feel any safer.  

Douglas London is the author of “The Recruiter: Spying and the Lost Art of American Intelligence” and served 34 years as a CIA operations officer, including multiple assignments as a chief of station and as the agency’s counterterrorism chief for South and Southwest Asia. He teaches intelligence studies at Georgetown University’s School of Foreign Service.