The rationale behind the creation of the secret civilian authority drew on the fact that the German and Soviet occupation of Poland was illegal. Hence, all institutions created by the occupying powers were considered illegal, and parallel Polish underground institutions were set up in accordance with Polish law. The scale of the Underground State was also inadvertently aided by the actions of the occupiers, whose attempts to destroy the Polish state, nation, and its culture, including most importantly genocidal policies that targeted Polish citizens, fuelled popular support for the Polish resistance movement and its development.