Strike could lengthen war

Patrick Regan is a professor of peace studies and political science at the Kroc Institute for International Peace Studies, University of Notre Dame, who studies violent armed conflict and its resolution:

A significant amount of research, including my own, demonstrates that military interventions from outside states lengthen and make bloodier civil wars. Much of this evidence is the result of statistical modeling of all civil wars and any associated interventions. The data include roughly 1,000 interventions into 100 civil wars over the last 60 years, with research carried out by multiple research teams.

The results point to patterns in what happens when states intervene to try to help their preferred actor, and the results are strong and consistent that interventions rarely work to promote peace or reduce violence. For example, my own research has shown that the likelihood of a civil war lasting for four years without an intervention is 37%, but if there is an intervention the likelihood that it lasts for four years is 60%. The intervention accounts for the 50% increase in the length of the war.

Longer wars are generally bloodier. Examples might include the Nicaraguan war in the 1980s, and the Syrian war up to this point. The meager support for the rebels has allowed them to push harder against the government, and whether or not we support the government, the killing and the war’s duration has only increased.

[…] Even if a U.S. missile strike reflects inadvertent help for the rebels, history does not point to a good outcome for U.S. policy.
The only pathway by which external interventions consistently make for shorter or less bloody wars is through diplomatic efforts to broker a peace agreement. The same modeling evidence suggests that the war in Angola, 1975-1991, could have been shortened by nearly 10 years with well-timed diplomatic interventions.