@petergleick "Why should he balk at committing war crimes?"

Because he's a bully. Like all bullies, he only escalates if he thinks he can get away with it. This is his constant calculation. He learns when and where there is pushback and he avoids similar situations because he fears being exposed. At the same time, he always attacking what he thinks are the easiest targets. When he succeeds in gaining a capitulation, he feels validated.

On the other hand, when we push back, we expose his weakness and the essential hollowness of him and his threats. He might trial (as all trolls do) pushing against the boundaries, but in the end we all know (as does he, deep down) that he will back down in the face of real opposition.