Complex sentence: The IPN maintains that accurate figures for these losses are not available because of border changes and population transfers, according to their figures 308,000 Polish citizens from the ethnic minorities were deported into the interior of the Soviet Union and were into the Soviet armed forces.
Split into simpler sentences: The IPN maintains that accurate figures for these losses are not available because of border changes and population transfers. According to IPN figures 308,000 Polish citizens from the ethnic minorities were deported into the interior of the Soviet Union; in addition they were conscripted into the Soviet armed forces.