The US “took the shot” on 31 July that killed Aymen al-Zawahiri, the identified leader of Al-Qaeda.  Zawahiri had been hunted by the US since the 9-11.  It took a decade to find and kill Osama bin Laden.  It took another decade to find and kill Zawahiri.  There was general celebration of this achievement in Washington. 

There’s a good chance this was a good thing to do. It would have been difficult for a president not to follow-through on killing Zawahiri.  Imagine the leaks to the press about the president who had the second person responsible for 9-11 in his drone sites and did not pull the trigger.

Still it is interesting to consider the alternative. It is fundamental to ignore sunk costs in cost-benefit analysis. The objective is to evaluate expected future returns/risks of a potential action. It’s the future that we can affect. 

Presumably someone in the Administration considered the benefits of leaving Zawahiri alive.  Here are a few possible benefits:

1. Zawahiri was the aging (71) head of a greatly weakened organization.  He had the stature of being the second to al Qaeda founder Usama bin Laden but lacked the organizational skills and charisma of UBL.  In the decade since UBL was killed, he has not been successful in rebuilding Al Qaeda.  Offshoots in Mali, Somalia, and Yemen are more localized, with local leaders and local objectives.  Under Zawahiri the threat to the US homeland has been constrained. 
2. Removing Zawahiri opens the leadership position to someone who may be more energetic and wanting to make a name by hitting the US directly.  With the US being pressed from many sides, it’s somewhat surprising we have not been hit again. In any case, Zawahiri was a devil we knew and his track record for the last decade is limited.
3. A new leader will lack the inherited respect accorded to Zawahiri.  A younger leader may seek to demonstrate leadership by re-igniting the war against the far enemy (US) in an effort to rebuild al Qaeda internationally.
4. The fact that the US killed the titular head of Al-Qaeda makes his death a rallying point for invigorated anti-US activity, beyond the localized threats in Africa and the Gulf.
5. The US may have solved a key management problem for Al-Qaeda.  It may be that the organization was suffering under old, weak leadership that could not be challenged directly.  The death of Zawahiri could make way for a new more dangerous Al-Qaeda.

This last point could produce some creative theories about how the US located Zawahiri.  Perhaps the stymied young and hungry found salvation by letting the US solve their impatience with aged leadership.  Letting slip location information is certainly possible.  It’s pure speculation, but not useless. 

In any case, it is a certainty that US analysis of the threat posed by Al-Qaeda post-Zawahiri will be written…carefully.  Analysts in the intelligence community would find it awkward to assess that Al Qaeda could now become a greater threat to the US homeland.

An alternative that might have been considered (I have no clue) to create a third option for the president would be to simply release the image of Zawahiri in the crosshairs.  This would communicate a different message, but almost as powerful, i.e. Zawahiri was alive only because the US let him live.  This would weaken him further, block ascension of a more energetic dangerous leader, and, still put the Afghanis on the spot for harboring Al Qaeda leadership.

But that option may also have been impossible in Washington.  In political science it is impossible to ignore sunk costs.  The events of 9-11 are not just “sunk costs”.  It was an attack on the US that the US vowed to avenge—even if it took two decades to find Zawahiri. There are domestic political considerations not least is the debt to those most affected by 9-11.

Moreover, there may have been many other sensitive information of dynamics that made taking the shot inevitable. 

Still it is worth considering the alternatives.  In retrospect, there seems to be mixed views on the wisdom of killing Iranian Quds force leader Major General Qasem Soleimani.  For all Soleimani’s actions against the US, he was also someone with whom there was tacit coordination in fighting the common enemy of ISIS in Iraq (see Michael Gordon’s exquisite new book on the ISIS war, “Degrade and Destroy”.)

Perhaps most important, I hope the president’s staff did their best to preserve his options and not box him in.