It helps the student to gain a better perspective when the following document is read. Pius relied on information sent to him from across Europe - occupied and free. Much of that information came from the network of nuncios who, in turn, drew their information from a variety of sources, some accurate, others less so.
In this document the German nuncio, Cesare Orsenigo, relays a report given to him by "religious persons" who have recently visited Lvov in Soviet-occupied Western Ukraine / Poland. The account described the process of Soviet despoliation of Church property. What was particularly notable was the reference to the Jews.
Orsenigo's information was partially true but not completely accurate.
Many Jews in Western Ukraine welcomed the Soviet invasion but there were many who did not. At first, the Soviet occupation indulged in a propaganda battle to convince the newly "liberated" people of the freedom they would now enjoy as Soviet citizens now safe from the twin evils of Polish democracy and German Nazism. For Jews this was not all bad; the discrimination imposed by the Polish governments in the 1930s were now lifted. To many non-Jews this became evidence of the pre-disposition Jews had towards Bolshevism. It was to be a deadly myth that served an even deadlier purpose a few years later.
Orsenigo's report was written in late November after the sham elections were held in October 1939 with the unsurprising victory of the communist delegates and the escalation of Sovietisation including the beginnings of collectivisation of land, persecution of non-communists and the closing of all institutions that did not accord with the Soviet world-view, especially religious institutions.
In the absence of more reliable news, Pius and the Secretariat of State had to read, discern and balance the data they received. It was a very difficult task and lends credence to later claims that news was often very difficult to verify.