In October 2020 a North Korean soldier was killed by a landmine near the Chinese border. The soldier mishandled the mine while planting it. The government tried to keep this incident secret because they did not want the world to know they had begun using lethal landmines along portions of their 1,400-kilometer Chinese border. Until now these lethal mines were only used along the DMZ (Demilitarized Zone) with South Korea, and experienced engineer units handled that. There have been mines on the Chinese border but these did not contain a lethal quantity of explosives and were meant to alert border guards that someone had gone into a forbidden area. The non-lethal mines were more convenient because many civilians entered these areas to collect firewood or edible plants and mushrooms. The non-lethal mines made it easier for the troops to rush into the area to search for suspected smugglers.
The lethal mines were now being placed in remote areas known to be heavily used by smugglers and at the moment the government is also intent on keeping out smugglers infected with covid19. Several such outbreaks of covid19 in North Korea have been traced back to smugglers. The government also wants to keep that secret but the chatter and rumor network in North Korea is well developed and important information gets around and eventually crosses the border into China.
Landmines are a big deal in Korea. Although the Korean War ended in 1953, there continue to be casualties from that conflict every year. That’s mainly because of landmines and unexploded munitions still buried along the DMZ, which was the front line when the fighting stopped in June of 1953. Growing prosperity in South Korea over the last three decades has led to more construction near the DMZ and sometimes fatale encounters with lost landmines and other explosive devices.
In the last decade South Korean troops have found and removed 100-200 landmines a year. Since 1998, when South Korea launched a major effort to remove Korean War (1950-53) era landmines, over 70,000 have been found and removed. This mine clearing campaign is part of a larger plan to eventually remove all landmines from South Korea and North Korea.
While landmines are technically "banned" weapons, there are still plenty in use and one of the most mined areas is Korea. The Mine Ban Treaty came into force in 1999, but 42 countries did not agree to the ban on the production, stockpiling, and use of antipersonnel mines. Countries who opted out include China, India, Pakistan, Russia, South Korea, and the United States. This list includes the major producers of landmines, as well as many of those still using landmines.
South Korea has about a million landmines emplaced along the DMZ. Since 1953 the four-kilometer-wide DMZ has provided an impenetrable 250-kilometer barrier across the Korean peninsula. The U.S. and South Korea have another two million or so mines in storage, in case North Korea tries to invade again, as it last did in 1950. North Korea won't say how many mines it has planted but it's probably at least several hundred thousand.
South Korea has to replace mines as they get too old to still work, and in the last decade they have been doing this with a new generation of command (by wire or wireless) detonated mines. Many of the more recent mines South Korea has stockpiled are of the self-destruct (a certain amount of time after planted) variety. South Korea has been making plans for clearing all the mines it has planted over the years, largely because it appears that the communist government of North Korea will collapse eventually, eliminating the need for the DMZ and all those mines.
Despite these mine clearing efforts, there is no quick way to clear all landmines. That’s because many of those planted during the Korean War were not recorded or records of these mine fields were destroyed during combat or lost after the war. Even mines with a recorded location can be shifted by landslides or heavy rains. Old mines and unexploded bombs and shells will continue to show up for decades. Such has been the case in the United States, where explosives from the Civil War (1861-65) still get found. Similarly, in Europe the tens of millions of mines and unexploded munitions are regularly being encountered by farmers or construction crews.