Why the Korean DMZ Would Be Hell of Earth if War Broke Out

 In Land, North Korea, South Korea, N11

Key point The DMZ is full of mines and is sur­round­ed by two pow­er­ful armies. North Korea would cer­tain­ly also try to strike quick­ly and hit Seoul.

The recent defec­tion of a North Korean sol­dier across the demil­i­ta­rized zone (DMZ) that sep­a­rates the two Koreas high­light­ed how dif­fi­cult it is to cross from one Korea to the other. Fenced, mined and patrolled by sol­diers from both sides, for­ti­fi­ca­tions and large con­cen­tra­tions of combat-ready troops will make the Korean DMZ in the event of war the dead­liest place on earth.

The cur­rent demar­ca­tion line between North and South Korea was set­tled by the Korean Armistice Agreement of July 1953. The two sides agreed on a demil­i­ta­rized zone approx­i­mate­ly 2.5 miles wide approx­i­mate­ly 160 miles long, bisect­ing the penin­su­la. Technically there is no “border,” as nei­ther Korea really con­sid­ers the other Korea sep­a­rate coun­try, and so the DMZ has become the de facto border. Although the DMZ is com­mon­ly referred as fol­low­ing the thirty-eighth par­al­lel line, it actu­al­ly falls beneath the thirty-eighth par­al­lel in the west and goes above it in the east.

North of the DMZ, the Korean People’s Army is respon­si­ble for the DMZ. (Although a Border Security Bureau exists, it pro­tects only the bor­ders with China and Russia.) North Korea has erect­ed a series of for­ti­fi­ca­tions and defen­sive struc­tures designed to pre­vent South Korean forces from cross­ing the border. An elec­tri­fied fence runs the length of the DMZ, along with mine­fields strewn with antiper­son­nel mines. The KPA has also built a number of towers designed to watch for South Korean incur­sions.

North Korea’s armed forces number 1.2 mil­lion armed men and women in uni­form, and the armed forces main­tain a decid­ed­ly offen­sive stance. Approximately 70 percent of ground forces and 50 percent of air and naval forces are within sixty miles of the DMZ. North Korea built several underground tunnels that crossed the DMZ, with at least four having been detect­ed — and sealed — by the Republic of Korea Army between 1974 and 2000. Starting in the early 2000s, Pyongyang report­ed­ly began build­ing a net­work of at least eight hun­dred bunkers near the border, each capa­ble of shel­ter­ing 1,500 to 2,000 KPA light infantry troops to act as pro­tec­tive mar­shal­ing points before the troops spear­head a cross-border assault.

In the event of war, North Korea’s plan is to use over­whelm­ing fire­pow­er and speed of action to con­duct a “One Blow Non-Stop Attack.” In 1992, Kim Jong-il, the father of cur­rent leader Kim Jong-un, con­clud­ed that only a light­ning assault across the border, known as “Occupying South Korea, All the Way to Pusan, in Three Days” could suc­ceed in light of the over­whelm­ing fire­pow­er that U.S. forces could bring to blunt any of Pyongyang’s moves.

Once war begins the KPA’s three for­ward infantry corps, the I, II and IV Corps, sup­port­ed by inde­pen­dent light infantry brigades and the 620th and Kangdong Artillery Corps, would launch a light­ning attack across the DMZ. Also in sup­port would be KPA Air Force fight­ers, heli­copters and fixed-wing air­craft flying com­man­dos, para­troop­ers and sabo­teurs south of the border, and amphibi­ous assaults on tac­ti­cal­ly sig­nif­i­cant South Korean islands and coastal areas. KPA sub­marines would fan out to deploy naval com­man­dos and inter­cept ROK Navy and U.S. Navy forces, par­tic­u­lar­ly amphibi­ous forces poised for a coun­ter­at­tack.

The vig­or­ous attacks by the three KPA corps — almost cer­tain­ly sup­port­ed by generous amounts of chemical weapons—would ide­al­ly gen­er­ate at least one break­through on the west and east coasts, with the west more impor­tant due to the pres­ence of the South Korean cap­i­tal of Seoul. On the west coast, the KPA 815th Mechanized Corps and 820th Tank Corps, each with hun­dreds of tanks and infantry fight­ing vehi­cles stand ready to exploit any break­through, while the 108th and 806th Mechanized Corps stand ready to do the same on the east coast.

North Korean heavy-artillery units such as the 620th and Kangdong Corps would fire from pro­tec­tive posi­tions known as Hardened Artillery Sites, or HARTS. Dug into moun­tain­sides and fre­quent­ly pro­tect­ed with con­crete case­ments, HARTS are designed to pro­vide an ele­vat­ed perch from which heavy artillery can fire their guns south in sup­port of an inva­sion — or to con­duct terror attacks on Seoul. The sites allow North Korean artillery to launch their deadly artillery strikes and then retreat into the bowels of a moun­tain, hill­side, or rough ter­rain to hide from U.S. and South Korean air­craft, artillery and mis­siles. Many HARTS sites have already been iden­ti­fied, but undoubt­ed­ly some will remain unde­tect­ed. Their abil­i­ty to target civil­ians makes them a number-one pri­or­i­ty in wartime.

Meanwhile, south of the DMZ, South Korea too has exten­sive defens­es designed to stop an army from cross­ing the border. Republic of Korea Army troops reg­u­lar­ly patrol the border, inspect­ing it for signs of infil­tra­tion, with heavy machine guns and other sup­port weapons over­look­ing key areas. (ROK sol­diers patrolling in the DMZ are considered “armed police” and not “military,” a dis­tinc­tion with­out a dif­fer­ence but within the letter of the armistice agree­ment.) In 2010, the SGR-1 armed border sentry robot began patrolling the DMZ, reflect­ing the high man­pow­er costs asso­ci­at­ed with cov­er­ing the entire­ty of the 160-mile-long zone.

There are also heav­ier, more obtru­sive defens­es for keep­ing armored and mech­a­nized forces out. Many roads and high­ways between Seoul and the DMZ are designed to be easily blocked in case of inva­sion. Roadways run­ning north-south are chan­neled through narrow passes that are easily blocked to the heav­i­est and most pow­er­ful tanks, includ­ing cylin­ders of con­crete sus­pend­ed by cables and pil­lars that are easily top­pled. These so-called countermobility obstacles are not designed to per­ma­nent­ly stop advanc­ing KPA forces, but just to slow them down long enough so that the defend­ers can mount an effec­tive defense.

In the event the North stages a cross-border attack, Southern troops would attempt to stop KPA forces as close to the border if pos­si­ble. Seoul is a mere half hour’s drive from the DMZ, and urban sprawl means even a minor pen­e­tra­tion would reach the out­skirts of the city. ROK forces at the border would be out­manned but per­haps not out­gunned, as KPA mil­i­tary tech­nol­o­gy lags far behind the south. Southern forces would throw every­thing they had at the enemy cross­ing the DMZ, and the amount of fire­pow­er traded north/south in some sec­tors could easily equal the fight­ing on the Somme or D‑Day.

In any cross-border attack, the longer it takes for the KPA to win, the more likely it is the United States and South Korea will pre­vail. An extend­ed offen­sive means more time for the ROK mil­i­tary to call up reserves and, per­haps more impor­tant­ly, more time for American air, ground and naval units to arrive and through their weight into the fight. In response, part of the KPA’s battle plan is to attack air­fields, ports, and other points of entry into the penin­su­la, seal­ing it off from rein­force­ments and giving time for the front­line combat units to win the war.

The Korean DMZ is almost cer­tain­ly the most heav­i­ly armed place on Earth. In the event the unthink­able hap­pens, the pres­ence of three large armies on the Korean Peninsula and their asso­ci­at­ed fire­pow­er would make the oth­er­wise peace­ful 2.5‑mile-by-160-mile strip (which dou­bles as a wildlife refuge) one of the dead­liest bat­tle­grounds ever con­ceived.

Kyle Mizokami is a defense and nation­al-secu­ri­ty writer based in San Francisco who has appeared in the Diplomat, Foreign Policy, War is Boring and the Daily Beast. In 2009, he cofound­ed the defense and secu­ri­ty blog Japan Security Watch. You can follow him on Twitter: @KyleMizokami. This first appeared in 2017 and is being repost­ed due to reader inter­est.

Image: Reuters

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