Speaking of the current Russia-Ukraine crisis, here is an interesting but less visible international legal dimension to the story.
Ukraine used to be part of the Soviet Union, during which time it had possessed huge stockpile of nuclear weapons arsenal – actually the third largest stockpile in the world at the time. Russia would not have ventured into Crimea today had Ukraine maintained possession of those nuclear weapons. What happened in 1994 was dramatic, and a bit embarrassing for Ukraine. At the end of the Cold War Ukraine agreed to an international deal that would deprive it of the entire nuclear weapon stockpile in its territory, mostly being transferred to Russia. In exchange, Russia, the US, and UK signed a binding pledge, the so-called Budapest Memorandum, guaranteeing the security of Ukraine. Now, what is interesting about this Memorandum is that it actually contained zero added-value as it offered Ukraine nothing other than what general international law already provided. Let me walk you through all the five articles of this Memorandum (yes it contained only five articles).
Article one states that Russia, USA and UK reaffirm their commitment to ‘to respect the independence and sovereignty and the existing borders of Ukraine’. Why is this promise useless? Because article 2(4) of the UN Charter, which has since become customary international law and even arguably a peremptory norm, already prohibits states from using ‘the threat or use of force against the territorial integrity or political independence of any state.’ Respecting the territory, independence and sovereignty of Ukraine is a customary international rule, and no additional treaty is needed for that.
Article two of the Memorandum basically repeats the above point, stating that the three powerful states will ‘refrain from the threat or use of force against the territorial integrity or political independence of Ukraine’, and adds that ‘none of their weapons will ever be used against Ukraine except in self-defence or otherwise in accordance with the Charter of the United Nations.’ This article seems to waste two clauses to say one and the same thing: what is the difference between ‘refraining from threatening or attacking’ another country and promising one’s ‘weapons won’t be used against’ such other country? Or the difference between saying ‘I will not attack you’ and ‘none of my equipment will be used to attack you’? One may say the first formulation concerns the actions of the attacker only while the later formulation creates responsibility on such party for the consequences of its weapons, by whomever the weapons may be used. That is to say, the first clause guarantees Russia, USA, and UK wont attack Ukraine, while the subsequent clause guarantees that the nuclear weapons of these states won’t be used by themselves or any other state against Ukraine. In either case, in as long as the Memorandum only envisages scenarios where the three states would have some control over the use of their nuclear weapons, either by themselves or through proxies, the general international law prohibition on the treat or use of force adequately covers it. A state would be held through the rules of state responsibility even if it uses other states (or non-state actors for that matter) as its proxy to attack another state. In sum, in article two of the Memorandum, Russia, USA, and UK promised not to attack Ukraine – but international law would not have allowed them to even if they had not made that promise.
Article three of the Memorandum guarantees that Russia, USA, and UK would ‘refrain from economic coercion designed to subordinate to their own interest the exercise by Ukraine of the rights inherent in its sovereignty.’ This seems to offer something distinct. Although unacceptable, there is no concrete rule under international law that prohibits the use of economic coercion against states (during the preparation of the UN Charter economic coercion was proposed to be prohibited together with the threat or use of force, but the proposal was rejected). However, the 1975 Final Act of the Conference on Security and Cooperation in Europe (Helsinki Accords) to which Ukraine and the three powerful states are members already prohibits the use of economic coercion against states. Article three of the Budapest Memorandum, therefore, is simply redundant.