Were the Nazis always killers?

First, I'm not quite sure what you mean by "nonviolent citizen-based defense." Second, It Seems To Me that nonviolent opposition only works against an enlightened, liberal, democratic government where public opinion matters.

The Soviet Union. Conditions and events during the German occupation of major sections of the Soviet Union during World War II differed vastly from those prevailing in India during the British occupation. However, German experiences also led certain officials of Nazi agencies and officers of the army to the view that the cooperation and obedience of the population of these territories were needed in order to maintain the occupation regime.

In accordance with their racial ideology and policies (especially that of replacing the existing population with Germans), for a long time the Nazis did not even seek cooperation from the Eastern Untermenschen (subhumans). This case therefore represents an absence of cooperation by the population of the occupied areas rather than a deliberate refusal of cooperation when sought. The situation is not always clear, for many factors influenced the course of the occupation. The role of the absence of cooperation in the occupied territories is itself sometimes difficult to isolate, because of the war and guerrilla activities in these territories. Nevertheless, despite ideology, Nazi policies and war, some German officials and officers very significantly concluded that the subjects' cooperation was needed.

In his study of the occupation Alexander Dallin is able to cite many instances of Nazi officials and army officers who came to realize the need for such cooperation. For example, Kube, the Reichskommissar in Belorussia, slowly and reluctantly concluded that at least the passive support of the population was needed. In 1942 he became convinced, Dallin reports, "that German forces could not exercise effective control without enlisting the population." Dallin also quotes a statement by German military commanders in the Soviet Union in December 1942: "The seriousness of the situation clearly makes imperative the positive cooperation of the population. Russia can be beaten only by Russians." Captain Wilfried Strik-Strikfeldt expressed similar views in lectures before a General Staff training course: "Germany, Strik-Strikfeldt concluded, faced the choice of proceeding with or without the people: it could not succeed without them if only because such a course required a measure of force which it was incapable of marshalling." General Harteneck wrote in May 1943: "We can master the wide Russian expanse which we have conquered only with the Russians and Ukrainians who live in it, never against their will."

Reviewing the history of the German occupation of the Soviet Union, Dallin writes:

While the whip continued to be the rather universal attribute of German rule, there slowly matured an elementary realization that the active cooperation of the people was needed for maximum security and optimal performance. A pragmatic imperative, perceived primarily in the field, dictated a departure from the practice, if not the theory, of Nazi-style colonialism.

I do want to know more about what you mean by nonviolent citizen based defense.

I am being terribly succinct -- please tell me if you need anything to be expanded on.