This is a very important new development and has major implications for war. Nowadays, we want to be stern but non-confrontational. We strike the enemy, but not hard enough to prevent them from burning and pillaging. After all, that would damage their egos, and we don't want to be the bad guys here. The new goal of warfare is to annoy the enemy into bargaining, but without giving them a negative self-image, or making yourself look like too much of a drag.
Bullies are unpopular.
We give the enemy the military and diplomatic equivalent of leaving the toilet seat up, or unscrewing the top on the salt shaker. You attack anonymously and covertly, whether by slashing your rival cheerleader's tires while she's in gym class, or by launching a barrage of faceless missiles toward Serbia in the middle of the night. Neither action will stop the problem, but they'll both remind the enemy that you may, one day, possibly think about really getting serious about solving the problem. Sending in ground troops would be way too harsh on the Serbs and would make us look like hall monitors butting in to break up the world's mischief too swiftly and arbitrarily. The times have changed.