Some 70 percent of North Korean ground forces are within a hundred kilometers of the DMZ (Demilitarized Zone, the border with the south). This is the main threat to South Korea but two decades of money, fuel, and food shortages have greatly reduced North Korean Army capabilities. Two decades of extreme poverty have done even more damage to the navy and air force. While the North Korean Navy was never meant to be a major factor, the air force was meant to be a crucial element in countering, for a few days at least, the far superior South Korean and American air forces. The North Koreans have been desperate to maintain and upgrade their air force but have been unable to do much since the 1990s. The last “new” aircraft North Korea was able to obtain were 40 MiG-21s, secretly purchased from Kazakhstan in 1999.
Recently, South Korea got to see how far gone the North Korean air forces were. Back in 2010, after North Korea attacked South Korea twice (sinking a corvette with a torpedo and shelling a town on a South Korean island near North Korea), there was a period of extremely high tension on the border. Both Koreas put their armed forces on alert, a higher alert than had been used for decades. What the South Korean intel analysts were particularly amazed by was the poor performance of the North Korean air force during this hasty mobilization as air patrols were greatly increased. It was known that North Korean pilots had been getting less and less flying time in the past decade, but when ordered into the air on a large scale for this hasty mobilization, the results were amazingly bad. The flying skills of combat pilots were particularly unimpressive, as was the performance of many aircraft (indicating poor maintenance). There were several crashes, many near misses in the air and a general sense of confusion among the North Korean Air Force commanders and troops. American and North Korean radars were able to record all this and satellite photos showed the aftermath.
While North Korea was apparently trying to impress, and intimidate, South Korea with this display of aerial might, the impact was just the opposite. With the exception of ten MiG-29s, the North Korean air force consists of 1,300 Cold War era Russian and Chinese aircraft, about half of them combat planes. The Chinese aircraft are knockoffs of older Russian designs, and most of the North Korean fleet consists of aircraft designs that were getting old in the 1970s. The North Korean Air Force training exercise merely confirmed what many South Korean and American intelligence analysts already suspected: that the North Korean Air Force could barely fly and hardly fight.
The most modern aircraft the North Koreans have are 40 MiG-29s they got in the 1980s, when they were still getting freebies from the Soviet Union. The rest of their combat aircraft are poorly maintained and infrequently used (because of fuel and spare parts shortages) antiques. There are 50 MiG-23s, an unreliable 1960s design which few other countries still use. There are about 190 MiG-21s (40 of them Chinese copies of the Russian design) and about 90 each of F-6s and F-5s (Chinese copies of the MiG-19 and MiG-17, both 1950s designs hardly anyone else uses). They have 160 bombers and ground attack aircraft, most of them elderly Russian and Chinese designs. The best of this lot are the 32 Su-25s, which are a decent contemporary of the U.S. A-10 that has proven itself in Afghanistan and the Caucasus.
The helicopter force is also elderly. The best of them are 20 Russian Mi-24 gunships and 80 American MD-500D, smuggled in from Germany in the 1980s. Perhaps the most dangerous aircraft are 300 AN-2 single engine bi-plane transports. A sturdy Russian aircraft which, although designed in the 1940s, was simple, rugged, popular, and remained in production until a decade ago. Able to carry ten passengers, the North Korean AN-2s have been seen practicing flying low and at night. Since each AN-2 can carry ten soldiers, it is believed they are meant to deliver commandos into South Korea early on in a war. Several thousand of these troops could cause a lot of confusion as South Korea mobilized for war. But in the last five years fuel shortages have meant few AN-2s have been flying. That means the pilots are not really skilled enough to carry off a night operation, especially flying low (to avoid radar) through the mountains separating the two Koreas. Using AN-2s now would lead to a lot of them, if not most of them, not making it. Then there are whatever surprises South Korea and the U.S. have developed to counter this daring use of AN-2s.
The North Korean generals are aware of their aircraft deficiencies and have tried to make up for it with a large anti-aircraft system. But they have mostly very old missiles and a lot of small-caliber anti-aircraft guns. The U.S. is very good at taking out radars and communications needed to make a nationwide anti-aircraft system work. It comes down to who is better prepared and equipped. The North Koreans might have some secret tricks but they definitely don’t have the tech or the track record that the U.S. possesses.
To make up for their lack of offensive aircraft, North Korea depends increasingly on ballistic missiles. The main weapon here is the liquid fuel SCUD, of which North Korea has about 500 in working order. The big drawback here is that it takes several hours to fuel these missiles. While this could be done in caves, the North Koreans depend on being able to keep the location of the caves secret. Otherwise the entrances will be bombed early on, leaving the missiles trapped underground and useless until dug out. The North Koreans believe that if they can develop compact and reliable nuclear weapons and equip some of their ballistic missiles with them, they will have a reliable weapon to protect the tyrants who run the country. At the moment, the air force is certainly not able to do the job.