Detailed Instructions: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: On 1 September, Germany invaded Poland from the west. Within the first few days of the invasion, Germany began conducting massacres of Polish and Jewish civilians and POWs. These executions took place in over 30 towns and villages in the first month of German occupation. The Luftwaffe also took part by strafing fleeing civilian refugees on roads and carrying out a bombing campaign. The Soviet Union assisted German air forces by allowing them to use signals broadcast by the Soviet radio station at Minsk allegedly "for urgent aeronautical experiments".
A:
How did the Russians communicate to the Germans in regards to bombing civilians trying to flee cities?