According to a recent Facebook post from the Department of War, DC is “SAFER THAN EVER BEFORE,” thanks to the National Guard’s presence there. But new analysis suggests that the costs of this supposed safety outweigh its benefits. 

the deployment was associated with declines in several public-facing crimes [like robbery and motor vehicle theft]. … However, several indicators point to a temporary reduction in local economic and social activity after the deployment. … These patterns suggest that some of the observed crime reduction may have reflected reduced mobility and commercial activity, rather than deterrence alone.

The researchers also performed a cost/​benefit analysis:

Over a 30-day period, the estimated social benefits from fewer robberies, thefts, and motor vehicle thefts totaled about $6.45 million. Estimated National Guard costs were roughly $89.86 million over the same period, implying that each dollar spent generated about $0.07 in estimated social benefits.

The 

analysis’s central conclusion is that visible military deployments may reduce some opportunistic street crimes in the short run, but they appear costly, limited in scope, and less efficient than sustained, community-based public safety strategies.