This is the 1500th most frequent Russian word.
оккупационные
"Occupational" or "relating to occupation (military occupation)."
In this sentence, 'оккупационные' is an adjective describing the troops that are related to occupation, specifically referring to military occupation of a territory.
Оккупационные войска покинули территорию страны.
The occupational troops left the territory of the country.
Here, 'оккупационным' is an adjective modifying 'управлением', referring to the state of being managed or governed in the context of occupation.
Город находился под оккупационным управлением несколько лет.
The city was under occupational administration for several years.
In this sentence, 'оккупационный' is an adjective describing 'режим', indicating that the regime pertains to occupation, imposed by external or foreign forces.