Defection = defection.
Do I need to explain that, descriptively, the difference between war and crime is a matter of degree? Am I explaining that the sun rises in the morning, or is this controversial?
It's defection, and the correct response is to neutralize the defector. In a war, there's a lot of defectors. Crime usually refers to a small handful. However, logically speaking, every crime is an act of war. If it's necessary to mobilize an army to put it down, then you mobilize an army.
Even something as little as bad words. If someone is speaking unkindly to you and refuses to stop when asked, you can go ahead and declare war on them, because they have already implicitly declared war on you.
Note that war is the default state of human groups, not peace. A formal peace treaty is necessary to define the conditions of cooperation, especially when communication is expensive or otherwise limited. Sans treaty, whoever first consciously realizes they're at war will gain an advantage.