Two days after bombing Hiroshima and the day before Nagasaki, the US, the Soviet Union, Great Britain, and France signed the so-called London Agreement, which made war crimes and crimes against humanity actions punishable in an international court.
But there was a catch. How could they prevent the condemnation of their own systematic bombing of civilian residential areas in Germany and Japan, according to the rules that had been accepted before the war as valid international law, even by the Allies themselves? What would they say when German generals, brought to court for destroying entire villages in actions against partisans, responded that they had done precisely what the Allied bombers had done to German cities and villages?
In his concluding report, prosecutor Telford Taylor declared both German and Allied bombing innocent, since ‘the air bombardment of cities and factories has become a recognised part of modern warfare, as practised by all nations’. The bombing of civilians had, according to the court, become customary law. The fourth Hague Convention of 1907, which forbids air bombardment of civilians, was not applied during the Second World War and thereby, according to the court, had lost its validity.
So rather than establishing that the Allies, too in fact, especially the Allies had committed this kind of war crime, the American prosecutor declared that the law had been rendered invalid by the actions of the Allies.