A collection of published materials contains 18 documents from the Soviet archives created by local organs of USSR's secret police that have been kept confidential until now. They concern various forms of the population attitudes against the Soviet policy aiming at sovietization and russification of Poland's eastern territories seized by the military aggression of 1939. These documents confirm the existence of strong resistance against the Soviet policy and various forms of activity of the Polish Underground, including military actions. NKVD and NKGB reports on agents operations aiming at liquidation of the Underground dominate among the documents, as well as reports on anti-soviet activity of intelligentsia, hostile speeches made during numerous events, holiday celebrations, local authorities election or activity connected with reclaiming land in excess of the established level from kulaks. These documents contain many facts and descriptions of events, some of them in detail, as well as evaluation of these events by the authorities.