Do Interventions Shorten Civil Wars?

by Patrick Appel

Roger Cohen believes so:

My sense is that Assad’s end would be hastened even by a limited U.S. attack. It should be framed as retribution for a heinous crime. It will not in itself solve anything—but then nothing will. It may, however, bring us closer to the end game.

But that’s not what research on the subject finds:

The data incorporate 150 conflicts during the period from 1945 to 1999, 101 of which had outside interventions. Using a hazard analysis, the results suggest that third-party interventions tend to extend expected durations rather than shorten them.