Is the marginal incentive to become a terrorist increasing or decreasing in the level of drone strikes?  In the former case, terrorist activity is a strategic complement to drone strikes and, in the latter, a strategic substitute.  Of course, the relationship may change sign with the level of strikes , e.g. at a medium level of drone strikes, terrorist activity is a complement but at very high levels it is a substitute (as we  kill terrorists more quickly than they can be created!).

This issue lies at the heart of the optimal policy of drone strikes.  Robert Wright asks whether hawkish policies:

“have, while killing terrorists abroad, created terrorists both abroad and — more disturbingly — at home.

These possibly counterproductive hawkish policies go beyond drone strikes — a fact that is unwittingly underscored by the hawks themselves. They’re the first to highlight the role played by that imam in Yemen, Anwar al-Awlaki, in inspiring Shahzad and other terrorists. But look at the jihadist recruiting narrative al-Awlaki’s peddling. He says America is at war with Islam, and to make this case he recites the greatest hits of hawkish policy: the invasion of Iraq, the troop escalation in Afghanistan, drone strikes in Pakistan, etc.”

Wright adds:

“Unfortunately, President Obama isn’t discarding the Bush-Cheney playbook that has given jihadist recruiters such effective talking points. Quite the contrary: the White House thinks the moral of the Shahzad story may be that we should get more aggressive in Pakistan,possibly putting more boots on the ground. And already Obama has authorized the assassination of al-Awlaki.

Even leaving aside the constitutional questions (al-Awlaki is an American citizen), doesn’t Obama see what a gift the killing of this imam would be to his cause? Just ask the Romans how their anti-Jesus-movement strategy worked out. (And Jesus’s followers didn’t have their leader’s sermons saved in ready-to-go video and audio files; al-Awlaki’s resurrection would be vivid indeed.)”

David Jaeger and Daniele Paserman have done empirical work on this issue in the context of the Israeli-Palestinian conflict.  In one paper they find that Israeli fatalities in the last period are a good predictor of Palestinian fatalities the next (strategic complements) but Palestinian fatalities last period are not related significantly to Israeli fatalities the next.  It is not clear whether this translates to the Al Qaeda/Taliban context.  Surely the data is there somewhere to do the analysis.  Is Obama’s policy evidence-based or is he, as Wright suggests, just copying the Bush-Cheney playbook?