A state may intervene to assist an incumbent government if rebel groups are supported by another external state, and where such support sufficiently amounts to an armed attack (Nicaragua Case 1986 ICJ Reports 103-4).
There appears to be overwhelming verified evidence to confirm this is the situation taking place in Ukraine.
In such instances the intervening state acts in support of the incumbent government to exercise a right of collective self defense.
The ICJ has held in the past that it is lawful for a foreign state to give to a people struggling for self determination moral, political and humanitarian assistance, but it is not lawful for a foreign state to intervene in that struggle with force or to provide arms, supplies and other logistical support in the prosecution of an armed rebellion.
The unprecedented sanctions and military support provided by western countries to Ukraine is evidence of the ever developing international law according to pertinent present circumstances. This is a good thing.
It is however hoped that great Western Powers are not advancing their own ideological interests at the expense of the Ukrainian citizens; using the pretext of collective self defense to do so.
AH Quass
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