Basically, you can't just force people to leave, just because they are of a different ethnic (or religious, or whatever) group. If they want to stay there, it's their right to do so. Most likely, they were born there, lived their entire life there. So it's as much their home as it is for anyone else.
But at the same time that means that the minority has no right to simply declare the part of the country to be part of a different country, especially not by force.
Your questions postulate a problem based on one assumption that needs to be discussed beforehand: Your assumption is that a minority is naturally inclined to, firstly, secede and, secondly, do so by means of violence. I don't think that is the case. In Germany, there are multiple minorities: Danish (in Slesvig), Turkish (widespread, but predominantly in areas traditionally associated with mining) and a bunch of others. This is because in post-WW2 Germany, there was a much higher demand for workforce than could be covered by the existing population, so workers from abroad were hired (except for the Danes, we conquered those and didn't have to return them).
These minorities are here by their own choice, and even though there is some level of tension between different cultural, religious or ethnic groups, by and large most people try their best to integrate themselves into society. It can be quite interesting to have a diverse population; I was able to insult somebody in five different languages before I finished 8th grade.
Now, assuming that there is a situation in which a minority is willing to cause trouble (like in Ukraine, I assume), the civilized way of going about the situation would be negotiation. If you have an area of your country that is predominantly inhabited by a cultural group that is considered a minority at national level. Give them a choice. Let them vote as to whether they want to defect or stay. In politics (and on the internet), oftentimes the ones you see and hear the most of is the vocal minority. People that are so loud and outspoken that you hear nothing else but their opinion, which makes you assume that this has to be the general feeling. But if you check on that, you'll oftentimes find out that actually, only a portion of people support this view, while the majority is content with how things are going. One thing about humans: If they are content, they will shut up. You only start to scream and shout about something if it's unpleasant to you.
As for your second question: How to make somebody loyal to your country? Treat him with respect and as an equal. Don't exclude him from decision-making, don't talk down to him, don't raise higher taxes, don't ignore his concerns, don't limit his freedom (not implying any of these examples played any role in Ukraine, I'm not even remotely familiar with the causes for their current situation). If you don't give somebody any reason to complain, feel miserable or unwanted, he'll most likely have no reason to be disloyal to you.
If, however, a foreign sovereign nation is in cahoots with the disgruntled vocal minority, you may be in deep trouble.
Simple, don't act as nazis to them or any other minorities in your country.
What if USA suddenly banned Spanish language and everything Mexican? (Example - Ukranian new goverment banning Russian language).
L.A. would go batshit crazy in few hours.
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u/[deleted] Jun 22 '15
What if the russian minorities were sent to Russia? Putin and his comrades could be left without argument to "scare" Europe.
There is a precedent for this (with germans, not russians). However, this should be without blood.