Early in the regime's existence, harsh measures were meted out to political opponents and those who resisted Nazi doctrine (e.g., the Communists), a role the SA performed until the SD and Gestapo undermined their influence and took control of security in the Reich.[39] Because the Gestapo seemed omniscient and omnipotent, the atmosphere of fear they created led to an overestimation of their reach and strength; a faulty assessment which hampered the operational effectiveness of underground resistance organisations.[40] Antipathy to Hitler and his regime was not tolerated, so the Gestapo had an important role to play in monitoring and prosecuting all who opposed Nazi rule, whether openly or covertly.