Seoul As Hostage?

RealClearDefense has a discussion of this question: Could North Korea Annihilate Seoul with its Artillery? Conventional wisdom has said it could. The article argues the destruction has been overstated. It reports:

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.

This last point may be why Trump believes he can get tough with the Norks.