Convention (II) with Respect to the Laws and Customs of War on Land and its annex: Regulations concerning the Laws and Customs of War on Land. The Hague, 29 July 1899.
Regulations: Art. 23. Besides the prohibitions provided by special Conventions, it is especially prohibited
(e) To employ arms, projectiles, or material of a nature to cause superfluous injury;
Regulations: Art. 25. The attack or bombardment of towns, villages, habitations or buildings which are not defended, is prohibited.
Convention (II) with Respect to the Laws and Customs of War on Land and its annex: Regulations concerning the Laws and Customs of War on Land. The Hague, 29 July 1899.
International Humanitarian Law (IHL) Databases
ICRC
https://ihl-databases.icrc.org/en/ihl-treaties/hague-conv-ii-1899
Regulations: Art. 4
Prisoners of war are in the power of the hostile Government, but not in that of the individuals or corps who captured them.
They must be humanely treated.
All their personal belongings, except arms, horses, and military papers remain their property.
Regulations: Art. 23. Besides the prohibitions provided by special Conventions, it is especially prohibited
(c) To kill or wound an enemy who, having laid down arms, or having no longer means of defence, has surrendered at discretion;
Regulations: Art. 25
The attack or bombardment of towns, villages, habitations or buildings which are not defended, is prohibited.
Regulations: Art. 46
Family honours and rights, individual lives and private property, as well as religious convictions and liberty, must be respected.
Private property cannot be confiscated.
Regulations: Art. 47
Pillage is formally prohibited.
Regulations: Art. 50
No general penalty, pecuniary or otherwise, can be inflicted on the population on account of the acts of individuals for which it cannot be regarded as collectively responsible.
United States of America, Signature: 29.07.1899, Ratification / Accession: 09.04.1902
Japan, Signature: 29.07.1899, Ratification / Accession: 06.10.1900
China, Ratification / Accession: 12.06.1907
1899年のハーグ条約条約は、国際紛争の平和的処理、陸戦における法規、海上戦におけるジェネヴァ条約の適用、気球による爆発物の放出禁止、毒ガス禁止、ダムダム弾禁止の3つの条約と3つの宣言から成り立っている。これらの条約は、戦争の遂行を取り上げた初の多国間条約であり、国際紛争を解決するための強制仲裁のための拘束力のある国際裁判所の設立を定めている。
（日本が被害者になった）原爆投下が国際法違反だという場合、1899年のハーグ条約の Regulations: Art. 23 (e) と Art. 25 の違反を意味することが多い。
（日本が加害者になった）南京事件が国際法違反だという場合、1899年のハーグ条約の Regulations: Art. 4、Art. 23 (c)、Art. 25、Art. 46、Art. 47、Art. 50、の違反を意味することが多い。
私は、Regulations: Art. 25 を見て、すぐに東京への空襲を思い浮かべた。
どれが正しかった否かかではない。どれが違反していたか否かでもない。戦争はすべて正しくない。すべての国家が「1899年のハーグ条約」に違反している。