A 2011 study by the Nautilus Institute throws a considerable amount of cold water on this scenario. While the sheer number of artillery tubes could theoretically kill a large number of civilians, operational issues complicate matters and push the number of civilian casualties greatly downward. Despite the thousands of artillery pieces, only 700 heavier guns and rocket launchers, plus the newer 300-millimeter MRLs, have the range to strike Seoul. Only a third would normally be fired at once, and notional rates of fire would be slowed tremendously by the need to withdraw guns into their hardened artillery sites (HARTS) to shelter them from counter battery fire.

For most armies, artillery is just one component of an all-arms force consisting of infantry, armor and artillery. But North Korea’s curious strategic location, with the enemy capital within striking range, has turned the country’s arsenal of howitzers and rocket launchers collectively into a weapon of mass destruction, capable of reducing Seoul to rubble within days. Or does it? Has the threat to the capital by North Korea’s “King of Battle” been overstated?

During the Cold War, North Korea built up an oversized army—and artillery corps—as part of its goal of re-invading South Korea. The North Korean People’s Army Artillery Command is responsible for 12,000 pieces of tube artillery and 2,300 pieces of multiple launch rocket artillery over 107-millimeters. The majority of tube artillery are 122-, 130-, 152- and 170-millimeter units, and on the rocket side the majority are 240-millimeter units.

Artillery is particularly useful in Korea. The hilly, forested terrain common on much of the peninsula restricts line of sight, shortening direct fire ranges. Indirect weapons, such as howitzers, rocket launchers and mortars, can be useful for striking targets on the other side of a mountain or in a valley. Moreover, mountainous terrain may also block units from receiving long-range artillery support, making it vital for smaller units to have enough artillery firepower to conduct their own local attacks.

During peacetime, North Korean artillery is organized under the Artillery Command, which in turn falls under the Fourth Department of the General Staff’s Department’s Operations Bureau. In wartime, however, independent artillery units—where most of the heavy artillery is located—would be allocated to corps commanders responsible for carrying out the invasion.

North Korean units are generously supplied with artillery starting at the regimental/brigade level. Each infantry regiment, for example, not only has three infantry battalions but one battalion of eighteen 120-millimeter heavy mortars, another battalion of eighteen 122-millimeter howitzers, and a multiple rocket launcher (MRL) battery of nine 107-millimeter or 140-millimeter weapons. This ensures that regiments can act independently on the battlefield, carrying out attacks without support from headquarters if necessary.

At the next level up, a North Korean division typically has three artillery battalions, including one battalion of twelve 152-millimeter howitzers, two battalions with eighteen 122-millimeter howitzers and a MRL battalion of twelve 122-millimeter Katyusha truck-mounted MRLs. The result of all of this is a frontline combat division that has considerably more, on a tube-by-tube basis, firing units than a U.S. or South Korean division.

North Korea is known for some very big guns and MRLs, and these are allocated at the corps level. Each corps has twelve artillery battalions, or about twice as much as what could be expected to be allocated to a typical U.S. corps, split between six cannon and six MRL battalions. The cannon battalions are equipped with eighteen of the infamous 170-millimeter Koksan self-propelled howitzers, while the MRL battalions are equipped with eighteen 240-millimeter rocket launchers. During wartime, these are split into two or more Corps Artillery Groups and their firepower lent to support to critical operations—such as breaching the DMZ.

The world got a rare look at the preparedness of North Korean artillery units in November 2010, when the country conducted a surprise artillery attack on the southern island of Yeonpyeongdo. In preparation for the attack a battalion of twelve 122-millimeter MRLs was believed to have been moved onto the Kangnyŏng peninsula near Yeonpyeongdo. Such rocket launchers are division-level artillery and, according to 38North, this battalion is believed to have belonged to the nearby 33rd Infantry Division.

On November 23, the island was hit by two barrages totally 170 rounds of 122-millimeter rockets—and possibly some rounds from nearby 76.2-millimeter coastal artillery units. Republic of Korea (ROK) return fire was limited by an inoperative counter battery radar, which was repaired in time to direct a strike on North Korean rocket launcher units. Two civilians and two ROK Marines were killed in the attacks. Curiously, the rocket battalion should have been able to fire a total of about 288 rockets, but only 170 actually landed near the island. Of those 170 rockets, only 80 landed on the island itself, the rest in surrounding waters.

North Korea has also managed to turn its heavy artillery, particularly corps level 170-millimeter Koksan guns, 240-millimeter heavy rockets and new 300-millimeter MRLs into weapons of mass destruction. Since the 1990s, right about the time the Clinton administration decided not to undertake military action against North Korea’s nuclear program, the general consensus has been that Pyongyang had enough artillery to turn nearby Seoul, home to approximately 25 million South Koreans, into a “sea of fire” that could see up to one million civilians killed. This apocalyptic scenario has been a trump card against strong military action against Pyongyang, with fears it could order a bombardment of the city as an act of retaliation.

A 2011 study by the Nautilus Institute throws a considerable amount of cold water on this scenario. While the sheer number of artillery tubes could theoretically kill a large number of civilians, operational issues complicate matters and push the number of civilian casualties greatly downward. Despite the thousands of artillery pieces, only 700 heavier guns and rocket launchers, plus the newer 300-millimeter MRLs, have the range to strike Seoul. Only a third would normally be fired at once, and notional rates of fire would be slowed tremendously by the need to withdraw guns into their hardened artillery sites (HARTS) to shelter them from counter battery fire.

Other factors reduce the projected loss of life in the greater Seoul metropolitan area. The city has extensive air raid shelters for civilians that will quickly reduce the exposed population density. The North will struggle to keep these heavy artillery units supplied with shells, particularly with its aging supply system. Finally, U.S. and ROK forces will quickly begin hunting down units participating in the bombardment, causing their numbers to drop almost immediately.

Finally, the North would face a strategic dilemma. Artillery used to bomb Seoul could not be used to soften up border defenses for a general invasion, and in wartime it would be critical to capture the enemy capital quickly as possible. An all-out bombardment of the South Korean capital might very well leave Pyongyang without the ability to actually capture it, while at the same time ensuring a U.S./South Korean counteroffensive that would spell the end of the regime of Kim Jong-un. Even if a million civilians were killed in Seoul it would ensure Kim’s untimely demise, and from his perspective that is still almost certainly a very bad trade.

North Korean artillery will undoubtedly play a very large role in any future conflict. While the Korean People’s Army certainly has a large amount of cannon and rocket artillery, recent experience suggests that it falls short of its actual potential. Furthermore, while an artillery attack on Seoul would undoubtedly cause a great deal of civilian casualties, there are numerous factors involved that would give the North pause before unleashing such a scenario. This should not necessarily embolden hawks to use force against North Korea; the ideal future is still one in which the country’s plentiful artillery is not used at all.

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.