I don't think being paid in rubles is the necessary condition for knowing international law.
"War reparations are compensation payments made after a war by one side to the other. They are intended to cover damage or injury inflicted during a war. War reparations can take the form of hard currency, precious metals, natural resources, industrial assets, or intellectual properties. Loss of territory in a peace settlement is usually considered to be distinct from war reparations.
War reparations are often governed by treaties which belligerent parties negotiate as part of a peace settlement. Payment of reparations often occur as part of a condition to remove occupying troops or under the threat of re-occupation. The legal basis for war reparations in modern international law is Article 3 of the Hague Convention of 1907.[0]
