Personally I don't believe the term authoritarianism is a useful description of anything. It's too vague. I've seen one definition that's like "a system that rejects the involvement of certain groups or interests from the political process." Well that would be all socialist nations by default, since socialist countries by definition have denied political representation for the capitalist class in some way.

A better question is: How is a socialist country supposed to defend itself? It may not be possible for a country to achieve what Marx called upper-phase communism. It may not be possible for money, states, and all property to be abolished. That's a question for the future. But when a country tries to curtail the power of capitalists, even attempts to create what's known as true communism, they find themselves on the receiving end of an entire world against them. Sanctions, invasions, sabotage, spying. The shape that a socialist country will take is the result of its conditions. We're living in a world dominated by capital and socialist countries represent a resistance against capital. If socialist movements are threatened, they either defend themselves or collapse.

You're right that countries are dancing to the imperialists, because the imperialists hold the most power right now. That's why an anti-imperialist movement is important, why a multi-polar world is important. Once the threat of imperialism subsides or is defeated, then I'm going to guess socialist countries will begin to express their policies differently.

I don't think I'm comfortable with a central power having the authority to decide that certain groups don't have rights, that power is too often abused widely.

Is there any society that isn't this? A central authority deciding how to distribute rights is a governing body.

Socialism is a movement about denying the right of property to capitalists. That's the entire purpose of the movement, to elevate working class people to the point of dominating society and to restrain or abolish the capitalist class. Landlords and capitalists shouldn't be able to exercise the same rights they have in a liberal capitalist nation. Fascists, racists, transphobes, imperialists, etc shouldn't have any civil liberties and should be subject to arrest, reeducation, or worse.