The Polish resistance attitude towards railway sabotage was complicated. On one level, it was seen as a viable target of opportunity, disrupting the German war effort. At the same time, the Soviet Union, which had also invaded Poland in 1939, was seen as another enemy of the Polish state, and therefore there were debates within the Polish resistance loyal to the Polish government-in-exile as to what extent efforts aiding Soviet Union were in the best interest of Poland. As a result, the decision was made by the majority of the Polish resistance, affiliated with the government-in-exile and the Polish Underground State, to conduct only limited railway sabotage, while a plan for a wide-scale action aiming to totally disrupt it, codenamed "Akcja Bariera" was drawn up but shelved. The smaller communist-affiliated resistance, however, rejected this and supported extensive attacks at the German supply lines.