Not quite right. North Korea has always been squeezed between Japan and China. There is no evidence that The Soviets had very much to do directly with North Korea.
North Korea has indeed been propped up by Red China. NK imports most of its stuff from Red China. North Korea's economic problem has always been that it has nothing anybody wants and therefore has little to trade.
Who is the greatest threat to America, North Korea or terrorist? Answer: Liberals.