Prisoner of war in the context of "Joint Security Area"

Military occupation, also called belligerent occupation or simply occupation, is temporary hostile control exerted by a ruling power's military apparatus over a sovereign territory that is outside of the legal boundaries of that ruling power's own sovereign territory. The controlled territory is called occupied territory, and the ruling power is called the occupant. Occupation's intended temporary nature distinguishes it from annexation and colonialism. The occupant often establishes military rule to facilitate administration of the occupied territory, though this is not a necessary characteristic of occupation.

The rules of occupation are delineated in various international agreements—primarily the Hague Convention of 1907, the Geneva Conventions, and also by long-established state practice. The relevant international conventions, the International Committee of the Red Cross, and various treaties by military scholars provide guidelines on topics concerning the rights and duties of the occupying power, the protection of civilians, the treatment of prisoners of war, the coordination of relief efforts, the issuance of travel documents, the property rights of the populace, the handling of cultural and art objects, the management of refugees, and other concerns that are highest in importance both before and after the cessation of hostilities during an armed conflict. A country that engages in a military occupation and violates internationally agreed-upon norms runs the risk of censure, criticism, or condemnation. In the contemporary era, the laws of occupation have largely become a part of customary international law, and form a part of the law of war.

A neutral country is a sovereign state that is neutral towards belligerents in a specific war or holds itself as permanently neutral in all future conflicts (including avoiding entering into military alliances such as NATO, CSTO or the SCO). As a type of non-combatant status, nationals of neutral countries enjoy protection under the law of war from belligerent actions to a greater extent than other non-combatants such as enemy civilians and prisoners of war. Different countries interpret their neutrality differently: some, such as Costa Rica have demilitarized, while Switzerland holds to "armed neutrality", to deter aggression with a sizeable military, while barring itself from foreign deployment.

Not all neutral countries avoid any foreign deployment or alliances, as Austria and Ireland have active UN peacekeeping forces and a political alliance within the European Union. Sweden's traditional policy was not to participate in military alliances, with the intention of staying neutral in the case of war. Immediately before World War II, the Nordic countries stated their neutrality, but Sweden changed its position to that of non-belligerent at the start of the Winter War. Sweden would uphold its policy of neutrality until the 2022 Russian invasion of Ukraine. During the Cold War, former Yugoslavia claimed military and ideological neutrality from both the Western and Eastern Bloc, becoming a co-founder of the Non-Aligned Movement.

The Geneva Conventions is a term used to collectively refer to the four Geneva Conventions of 1949 along with their two optional protocols (Additional Protocols I and II), which form the core of international humanitarian law and establish international legal standards for the treatment of non-combatants in war. Negotiated in the aftermath of the World War II, the Geneva Conventions of 1949 consist of four agreements, which replaced three earlier humanitarian conventions of 1906 and 1929 and added two new conventions. The First Geneva Convention addresses the treatment of sick and wounded field soldiers, Second Geneva Convention addresses the treatment of sick and wounded sailors, Third Geneva Convention addresses the treatment of prisoners or war, and Fourth Geneva Convention addresses the treatment of civilians during armed conflict.

Aside from the UN Charter, the Geneva Conventions are among the most widely ratified international agreements. The 1949 conventions were ratified, in their entirety or with reservations, by 196 countries. Much of the international humanitarian law contained in the Geneva Conventions has become customary international law, and therefore would apply to all states and non-state armed groups, even those that are not a party to the Geneva Conventions. The legal obligations created under the Geneva Conventions are somewhat different from other international treaties in that a breach of the Geneva Conventions by one party does not furnish a directly affected party with the option to cease complying with its treaty obligations.

Combatant is the legal status of a person entitled to directly participate in hostilities during an armed conflict, and may be intentionally targeted by an adverse party for their participation in the armed conflict. Combatants are not afforded immunity from being directly targeted in situations of armed conflict and can be attacked regardless of the specific circumstances simply due to their status, so as to deprive their side of their support.

In an interstate conflict, the definition of "combatant" is found in Article 43 (2) of Additional Protocol I to the 1949 Geneva Conventions: "Members of the armed forces of a Party to a conflict (other than medical personnel and chaplains covered by Article 33 of the Third [Geneva] Convention) are combatants, that is to say, they have the right to participate directly in hostilities." Combatants when captured by an opposing party are automatically granted the status of protected persons, whether as prisoners of war or unlawful combatants.

The law of war is the part of international law that regulates the conditions for initiating war (jus ad bellum) and the conduct of hostilities (jus in bello). Laws of war define sovereignty and nationhood, states and territories, occupation, and other critical terms of law. Among other issues, the modern laws of war address the declarations of war; acceptance of surrender and the treatment of prisoners of war; the principles of distinction, as well as military necessity and proportionality; and the prohibition of certain weapons that cause unnecessary or excessive suffering.

The law of war is considered distinct from other bodies of law—such as the domestic law of a particular belligerent to a conflict—which may provide additional legal limits to the conduct or justification of war. The term law of war, or jus in bello, overlaps to some degree with opinio juris (also referred to as customary law), but refers to a very specific body of international law composed of customary and treaty-based law.

The Treaty of San Francisco (サンフランシスコ講和条約, San-Furanshisuko kōwa-Jōyaku), also called the Treaty of Peace with Japan (日本国との平和条約, Nihon-koku to no Heiwa-Jōyaku), re-established peaceful relations between Japan and the Allied Powers on behalf of the United Nations by ending the legal state of war, military occupation and providing for redress for hostile actions up to and including World War II. It was signed by 49 nations on 8 September 1951, in San Francisco, United States, at the War Memorial Opera House. Italy and China were not invited, the latter due to disagreements on whether the Republic of China or the People's Republic of China represented the Chinese people. Korea was also not invited due to a similar disagreement on whether South Korea or North Korea represented the Korean people.

The treaty came into force on April 28, 1952. It ended Japan's role as an imperial power, allocated compensation to Allied nations and former prisoners of war who had suffered Japanese war crimes during World War II, ended the Allied post-war occupation of Japan, and returned full sovereignty to it. This treaty relied heavily on the Charter of the United Nations and the Universal Declaration of Human Rights to enunciate the Allies' goals. In Article 11, Japan accepted the judgments of the International Military Tribunal for the Far East and of other Allied War Crimes Courts imposed on Japan both within and outside Japan.

Prisoners of war during World War II faced vastly different fates due to the POW conventions adhered to or ignored, depending on the theater of conflict, and the behaviour of their captors. During the war approximately 35 million soldiers surrendered, with many held in the prisoner-of-war camps. Most of the POWs were taken in the European theatre of the war. Approximately 14%, or 5 million, died in captivity; out of these, 3 million fatalities were Soviets POWs, and one million, German POWs.

Early in World War II, Nazi Germany, overwhelmed by the number of POWs, released many, though some became used as forced labor. As the war progressed, POWs became strategic assets, increasingly used as forced labor, or considered an important leverage for reciprocal treatment. Within a few years of the war ending, most of POWs were repatriated, though notable exceptions persisted, with Axis POWs in Chinese and Soviet camps held into the 1950s.