The totalitarian capitalist dystopia which was created by the United States in the aftermath of the Korean War has increasingly experienced problems as the multipolar world is being gradually birthed.
Due to the widespread exploitation of the population, long work weeks, and high housing prices, the population growth of South Korea has plummeted, with the lowest fertility rate on the planet, and the highest suicide rate in the OECD. While a capitalist "success story" before the 2008 recession in terms of profit accumulation for the richest at the expense of most others, conditions have grown more dire in the Long Depression since the crash. GDP growth per year has averaged out at 2-3%. For more concrete figures, labour productivity has stagnated, particularly in the service sector. The rate of profit hit a peak when the dictatorship ended in the late 1980s, but has since massively tumbled. These dynamics are not unique to South Korea; they are happening throughout the West.
While South Korea is stagnating, perhaps even falling, its northern neighbour is rising. With Russia already persona non grata to much of the developed world and yet still maintaining fairly good economic growth and continuously albeit gradually moving towards victory in Ukraine, Putin sees no reason to be intimidated by the West's shunning of the DPRK, and Russia is establishing ties as well as military and economic deals. This seems to portend an end to the post-Soviet period of forced isolation due to UN actions forbidding the people of the DPRK to leave the country (which many westerners believe is a policy originating from the Korean leadership due to their propagandized education).
Many in the West are still, regrettably, unable to properly analyze the geopolitical situation of Korea due to their government programming, leading to bizarre takes about imminent collapse, or desperation on the part of Russia or the DPRK, unable to recognize that the DPRK has a powerful military sector all its own, and decades of autarky has created a durable society where limited resources must be used efficiently and effectively. The position of the Korean Peninsula seems likely to be a critical part of the US-China conflict, whether this is an outright war or instead a series of proxy wars. Indeed, Korea's position may soon become very important in global trade routes if the US tries to cut off the Strait of Malacca to Chinese-bound cargo ships, with vital resources like oil and food potentially transported both over land and via the Arctic Route over Russia and through the DPRK to China. Russia's leadership clearly sees the importance of Korea in the future, hence their actions now; and, of course, South Korea siding with Ukraine has also forced Putin's hand to oppose them more openly.