Just barely. Had the military been just a bit more indoctrinated, they may have started shooting. Which, as far as I understand, were the instructions they received. If nothing else, if the legislators weren't able to get in, this would have gone a whole other way, and the coup could easily have been successful.
It's not about military indoctrination but the popularity of the leader. Yoon is exceptionally unpopular. If he had 80% approval, instead, he would probably now be the dictator of The People's Democratic Republic of South Korea.
Without that approval the best you're looking at (from his perspective) is mass unrest which an opportunistic nation like their neighbor could foment, support, and exploit.
If you've got 80% support in a democracy you don't need to declare martial law and overthrow the legislature: If you're that popular your party will easily secure a sizeable majority in the legislature and you can pass any law you want.
In fact, DPRK anticipated that Yoon Suk-yeol might attempt to ignite conflict on the peninsula to justify imposing martial law. Therefore, DPRK preemptively severed the roads between the two countries to prevent this from happening. Although DPRK is often scorned by the West, it is far more rational and stable than many other countries.
In the interest of Poe's law: that's not why DPRK has blown up the roads. It's because the current leader does not anticipate any cooperation or reunification with ROK in the future.
Very rational, except that the leadership is starving the population, banned the internet, and executes people by strapping them to anti-aircraft guns.
Oh and has send thousands of its citizens to die in Ukraine.
The history of North Korea is quite interesting. The mass starvation was in the 90s and mostly caused by US sanctions. They were wholly dependent on foreign imported oil both as fuel and as a way to make fertilizer with the USSR as their primary source.
When the USSR collapsed in the 90s, they no longer had any source for oil owing to sanctions. Their farming was thus severely impaired, and starvation was the predictable result.
We then post facto gave them emergency aid, likely with the idea of turning the people against their government and to the people starving them for geopolitics. Shockingly, it didn't work.
Their deepening relationship with Russia is mostly just a return to the past.
I think this is yet another example of how sanctions are quite a useless tool. If we'd straight up gone for the carrot (perhaps simply trading oil for arms at fair market rates) instead of waiting to starve people first, North Korea could very possibly be a friendly nation today.
Of course this sounds absurd only because most people don't realize South Korea was also under brutal dictatorships for most of its life since the Korean War (their first democratic election was in 1987) - big difference is those dictatorships were backed by the West and allowed to engage in more normal trade and development.
Realpolitik is far dirtier (and often painfully myopic) than most realize. I'd love to read a textbook about current times from a few hundred years from now...
