The seizure of oil and gas resources from the aspect of international law of belligerent occupation

Occupation of countries without permission and authorization of the UN organization, during the history, had been always a common issue. ISIS terrorist group during the many years of armed conflict with Syria and Iraq, regardless of the occupation of some of the territory of these two states, seized some oil and gas infrastructures and fields and measured to gain benefits from selling crude oil from those fields which is one of the most important source of revenue of ISIS. This group by selling the oil of Iraq and Syria earns three million dollars daily. USA government by occupation of Iraq in 2003, seized some oil and gas infrastructures and measured to sell the oil of this country. The issue of occupation is subject to international law of belligerent occupation and occupant forces cannot withdraw from the dominion of law and regulations. After belligerent occupation, some legal effects will be created which accordingly cause bringing up new issues in the field of occupation. Whether the officials of the occupant have the right of seizure and use of the oil and gas reservoirs and infrastructures?