While the deployment of the armed forces in Marawi and the use of necessary weapons and munitions to crush the Maute group are well within the Commander-in-Chief “calling-out” powers of the President (which did not require and does not require a declaration of martial law and the use of extraordinary powers), the airstrikes and ground offensives ordered by President Duterte are subject to and limited by Protocol 2 of the Geneva Conventions and, of course, by international conventions prohibiting “Excessively Injurious” weapons and weapons with “Indiscriminate Effects” (prohibited weapons such as incendiary bombs, cluster bombs, land mines, booby traps, etc.).
The following are the pertinent provisions of Protocol 2 of the Geneva Conventions (highlighted provisions in red font are prohibited acts, provisions in blue font are obligations on the part of the State)
Part IV. Civilian Population
Art 13. Protection of the civilian population
1. The civilian population and individual civilians shall enjoy general protection against the dangers arising from military operations. To give effect to this protection, the following rules shall be observed in all circumstances.
2. The civilian population as such, as well as individual civilians, shall not be the object of attack. Acts or threats of violence the primary purpose of which is to spread terror among the civilian population are prohibited.
3. Civilians shall enjoy the protection afforded by this part, unless and for such time as they take a direct part in hostilities.
Art 14. Protection of objects indispensable to the survival of the civilian population
Starvation of civilians as a method of combat is prohibited. It is therefore prohibited to attack, destroy, remove or render useless for that purpose, objects indispensable to the survival of the civilian population such as food-stuffs, agricultural areas for the production of food-stuffs, crops, livestock, drinking water installations and supplies and irrigation works.
Art 15. Protection of works and installations containing dangerous forces
Works or installations containing dangerous forces, namely dams, dykes and nuclear electrical generating stations, shall not be made the object of attack, even where these objects are military objectives, if such attack may cause the release of dangerous forces and consequent severe losses among the civilian population.
Art 16. Protection of cultural objects and of places of worship
Without prejudice to the provisions of the Hague Convention for the Protection of Cultural Property in the Event of Armed Conflict of 14 May 1954, it is prohibited to commit any acts of hostility directed against historic monuments, works of art or places of worship which constitute the cultural or spiritual heritage of peoples, and to use them in support of the military effort.
Art 17. Prohibition of forced movement of civilians
1. The displacement of the civilian population shall not be ordered for reasons related to the conflict unless the security of the civilians involved or imperative military reasons so demand. Should such displacements have to be carried out, all possible measures shall be taken in order that the civilian population may be received under satisfactory conditions of shelter, hygiene, health, safety and nutrition.
2. Civilians shall not be compelled to leave their own territory for reasons connected with the conflict.
Art 18. Relief societies and relief actions
1. Relief societies located in the territory of the High Contracting Party, such as Red Cross (Red Crescent, Red Lion and Sun) organizations may offer their services for the performance of their traditional functions in relation to the victims of the armed conflict. The civilian population may, even on its own initiative, offer to collect and care for the wounded, sick and shipwrecked.
2. If the civilian population is suffering undue hardship owing to a lack of the supplies essential for its survival, such as food-stuffs and medical supplies, relief actions for the civilian population which are of an exclusively humanitarian and impartial nature and which are conducted without any adverse distinction shall be undertaken subject to the consent of the High Contracting Party concerned.