From Service Graduates Against the War :
The U. S. Constitution, Art. VI, para. 2, makes treaties adopted by the U.S. part of the "law of the land." Thus, a violation of the U. N. Charter, Hague IV, Geneva Conventions, etc. is also a violation of U.S. federal law.U.S. Federal Law 18 U.S.C. § 2441 (War Crimes Act of 1996) makes committing a war crime, defined as: "...a grave breach in any of the international conventions signed at Geneva 12 August 1949, or any protocol to such convention to which the United States is a party..." punishable by fine, imprisonment, or death.
And the following treaties and charters which define: wars of aggression, war crimes, crimes against peace and crimes against humanity:
Laws and Customs of War on Land (Hague IV)
Art. 55. The occupying State shall be regarded only as administrator...of public buildings, real estate, forests, and agricultural estates belonging to the hostile State, and situated in the occupied country. It must safeguard the capital of these properties, and administer them in accordance with the rules of usufruct.
U.N. Gen. Assembly Res. 3314
Defines the crime of aggression as "... the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State...or in any other manner inconsistent with the Charter of the United Nations..."
Nuremberg Tribunal Charter
Principle VI: "The crimes hereinafter set out are punishable as crimes under international law:
(a) Crimes against peace: Planning, preparation, initiation or waging of a war of aggression or a war in violation of international treaties;
(b) War crimes: ...murder, ill-treatment...of civilian population of or in occupied territory; murder or ill-treatment of prisoners of war,...plunder of public or private property, wanton destruction of cities, towns, or villages...
(c) Crimes against humanity: Murder, extermination...and other inhuman acts done against any civilian population...when such acts are done...in execution of or in connection with any crime against peace or any war crime."
Geneva Conventions
A) Protocol I, Article 75: "(1)...persons who are in the power of a Party to the conflict...shall be treated humanely in all circumstances...(2) The following acts are and shall remain prohibited...whether committed by civilian or by military agents: (a) violence to the life, health, or physical or mental well-being of persons...(b) outrages upon personal dignity, in particular humiliating and degrading treatment, enforced prostitution and any form of indecent assault...and threats to commit any of the foregoing acts."
B) Protocol I, Art. 51: "The civilian population...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." Art. 57: (parties shall) "do everything feasible to verify that the objectives to be attacked are neither civilians nor civilian objects...an attack shall be cancelled or suspended if it becomes apparent that the objective is not a military one..."
C) Protocol I, Art. 70: "The Parties to the conflict...shall allow and facilitate rapid and unimpeded passage of all relief consignments, equipment and personnel...even if such assistance is destined for the civilian population of the adverse Party."
D) Protocol I, Art. 35: "In any armed conflict, the right of the Parties...to choose methods or means of warfare is not unlimited...It is prohibited to employ methods or means of warfare which are intended, or may be expected, to cause widespread, long-term and severe damage to the environment."
E) Convention I, Art. 3: "Persons taking no active part in the hostilities, including members of armed forces who have laid down their arms... shall in all circumstances be treated humanely...To this end, the following acts (in addition to those listed in Art. 75, above) are and shall remain prohibited:...the passing of sentences and the carrying out of executions without previous judgment pronounced by a regularly constituted court, affording all the judicial guarantees which are recognized as indispensable by civilized peoples."
F) Convention III, Art. 5: "Should any doubt arise as to whether persons, having committed a belligerent act and having fallen into the hands of the enemy (are prisoners of war under this Convention), such persons shall enjoy the protection of the present Convention until such time as their status has been determined by a competent tribunal."
G) Convention IV, Art. 33: "No protected person may be punished for an offence he or she has not personally committed. Collective penalties and likewise all measures of intimidation or of terrorism are prohibited."