The will of the people is not the top priority there.
If the people are properly consulted and the declaration of independence is a majority view, OR the body it is seceding from accepts the division, then both sides agreed to the split and it becomes an established international fact. Good example: the separation of Czechoslovakia.
If countries that are quasi independent choose to leave a union that they helped to create, that is a legal process leading to a legal fact.
If all members of a union of nations agree to terminate the union or accept in writing that it has already been dissolved, that again becomes a legal fact.
The USSR was terminated by the joint decision of the leaders of Ukraine, Belarus’and Russia. It’s not open to renegotiation. No matter what the public majority position was, governments can choose to end the treaties signed by their predecessors.
A popular of less than 5000 Russian settlers and pro Russian separatists arbitrarily declared themselves the governments of the Donbas without consulting the settled population of the region. They’ve refused point blank to prove there was any wider mandate in any election. As long as Ukraine views it as an illegal takeover by less than 1% of the population, Ukraine technically is in the right.
Likewise, China refuses to accept the independence ambitions of Taiwan. But unlike the Donbas, Taiwan isn’t seceding because of a 1% minority hijacking the administration.
RE: A popular of less than 5000 Russian settlers and pro Russian separatists arbitrarily declared themselves the governments of the Donbas without consulting the settled population of the region.
I’m just curious, where did you get the 5,000 figure from? I had the impression that it was much higher than that to a point where a referendum would be needed.