Surely it has? All those countries are crippled economically and only get attention on a global stage by saber rattling or when they decide to start looking to negotiate their way out.

I hardly think Kim Jong Un has "strengthened support" from NK citizens, bar the top elite. They just get shot if they step out of line.

Iran has a similar environment of fear, though not as totally controlling.

I'm not sure what Cuba is like for political repression, but the people are hardly supportive of the government as i understand it.

For what its worth, i don't believe imposing sanctions on Iran/Cuba is reasonable now. With the right diplomacy Iran looks to want to come to an agreement, and Cuba is no threat to anyone.

Russia is in a better position while they have support from China. But there is still an affect. Also, i don't think it's possible to happily trade with Russia as if they were an ally while Putin grabs land from other eastern European countries.