Complex sentence: The issue of Italian prisoners of war in the Soviet Union remained a hot political argument in post-war Italy; it was never seriously investigated because of the Soviet authorities unwillingness to yield information allowed no answer about the destiny of the tens of thousands of missing soldiers.
Split into simpler sentences: The issue of Italian prisoners of war in the Soviet Union remained a hot political topic in post-war Italy. It was never seriously investigated because of the Soviet authorities unwillingness to yield information about the destiny of the tens of thousands of missing soldiers.