North and South Korea Military Balance, by the Numbers

Richard L. Kugler, PhD/

Why North Korea’s Military Force Currently Could Not Conquer South Korea

Some  analysts fear that if the North Korean army invaded South Korea, the  North could quickly defeat South Korea’s army and overrun the entire  country. In my judgment, the South Korean army backed by U.S. air power  is plenty strong enough to rebuff a North Korean attack. Inevitably a  war on the Korean peninsula would be highly violent and uncertain, but  the odds are high that a North Korean attack would be stopped near the  Demilitarized Zone (DMZ), and immense losses would be inflicted on enemy  forces.

Data on the military situation in Korea is available  in IISS’s Military Balance 2017. On paper, the North Korean army seems  superior to the south. North Korea fields an army of a million troops  that includes 46 divisions, 4000 tanks, and 8500 artillery tubes for  firing conventional munitions. By contrast, South Korea fields a smaller  army of 500,000 troops that includes 30 divisions, 2400 tanks, and 5000  artillery tubes. But when an army is defending from prepared positions  on mountainous terrain, it does not need to be as large as its opponent.  This especially holds true in Korea, whose many steep mountains north  of Seoul make an enemy attack difficult. What matters is whether South  Korea has enough ground forces to form a strong defense line along the  160-mile DMZ and to mobilize sufficient reserves to block North Korean  forces from advancing down the few, small attack corridors along the  DMZ. The South Korean army is easily large enough and properly equipped  to perform this mission, and it has had over 60 years to prepare the  terrain north of Seoul with an extensive network of fortifications,  infantry trenches, tank barriers, and roadblocks that would impede a  North Korean assault.

An additional, important factor in the  military equation is the air balance, which strongly favors South Korea  and the United States. North Korea has a weak air force of 500 mostly  obsolescent fighters inherited from the Cold War. By contrast, South  Korea has 500 mostly modern fighters that include 200 F-15 and F-16s.  Within a few days, the United States could provide about 350 modern  fighters as reinforcements: all of them would be highly lethal against  North Korean air and ground forces. Together, South Korean and U.S. air  forces could quickly seize control of the air, devastate North Korean  ground forces caught in the open, and bomb such North Korean targets as  its artillery sites and Pyongyang.

The principal risk is that the  North Korean military, if unleashed by the country’s unpredictable and  pathological dictator, could employ its long-range artillery to bombard  Seoul and inflict major destruction on it. But the odds that North  Korean ground forces could conquer Seoul and advance deeply into South  Korea are low. The greater likelihood is that they would be stopped in  their tracks and destroyed by South Korean and U.S. forces, which would  be able to counterattack into North Korea in the aftermath. This  situation could change if and when North Korea acquires a sizable  arsenal of deliverable nuclear warheads in the years ahead. If this  occurs, the United States will be compelled to use its own nuclear  weapons to extend a firm umbrella of deterrence coverage over South  Korea. Until then, the current military balance in Korea is relatively  stable, and war is unlikely to occur provided South Korea remains  militarily strong and the United States continues using its power to  enforce containment and deterrence on the Korean peninsula.

In  summary, the military balance in Korea is undeniably something to worry  about, but in ways that keep matters in perspective. Yes, North Korea  today poses a major offensive threat to South Korea. But a North Korean  ground and air attack across the DMZ would encounter a strong South  Korean army, many mountains, extensive terrain fortifications and tank  barriers, and formidable U.S. and South Korean air strikes. Likely, the  North Korean military would come away battered and destroyed, not  victorious. This is a core reason why, despite many alarming political  crises, war has not broken out on the Korean peninsula since 1953, and  is unlikely to occur today.