When Robert Pape writes something on terrorism, I pay attention.  He always adds something to the discussion, and usually it's something valuable.  But his recent article on FP.com, "It's the Occupation, Stupid" delivers research results and leads the reader to an uncertain conclusion.  His argument holds that terrorism, especially suicide terrorism, is motivated by foreign occupation.  These findings, based on his research at the University of Chicago, make logical sense: of course people in an occupied territory resort to violence when all other means have been exhausted.  His conclusion from this study, however, is problematic.  Taking these findings to their logical end, Pape says

The research suggests that U.S. interests would be better served through a policy of offshore balancing.

This is true, but interpreted incorrectly can lead to a dangerous isolationism.  Pape is right that the War on Terror is self-defeating, and that having boots on the ground overseas can often be counterproductive.  He is also right that occupying foreign territory provokes deadly blowback.  But there are two important nuances to this argument:

1) Avoiding foreign occupation is not the same as withdrawing into isolation
2) Offshore balancing requires U.S. involvement and action in foreign countries, which could also instigate blowback.

First, it is important to recognize the difference between offshore balancing and isolationism.  It is tempting to extrapolate from Pape's argument that retreating into "Fortress America" is the wisest course.  But withdrawing from the world would not make America safer, and furthermore, in this global age, is impossible. 

Secondly, offshore balancing implies U.S. power projection overseas and involvement in the affairs of other states, and that doing so is in the best interests of Washington.  This could take the form of drone strikes, Special Operations raids, or even 1990's-style cruise missile attacks.  But this involvement could have a similar effect as foreign occupation: motivating terrorists.  This is a hole in Pape's data, and until further investigated remains a concern. 

There is no question that Pape's overall point is correct: foreign occupation is a major driver of terrorism, and removing boots from the ground is preferable.  But he would be wise to avoid leaving open the possibility of interpreting his findings to support isolationism.