By 2020 the Democratic People's Republic of Korea (DPRK) could possess as many as 100 nuclear warheads , allowing it to pursue war strategies that could hold the Republic of Korea and the United States hostage to the threat of devastating atomic attack. 
But North Korea's conventional weapons pose a major threat of their own, according to a January 2019 report from RAND, a California think tank with close ties to the U.S. military. 
"Even without using nuclear weapons, North Korea has the capacity to unleash a devastating level of violence against a significant portion of the ROK population through some mix of conventional artillery and possibly chemical munitions." 
A DPRK artillery barrage could inflict as many as 250,000 casualties in Seoul alone, RAND reported, citing a U.S. Defense Department estimate. 
"Conservative predictions of a likely attack scenario anticipate an initial artillery barrage focused on military targets, which would result in significant casualties," U.S. Army general Vincent Brooks, head of U.S. Forces Korea, told a U.S. Senate committee in March 2018. 
"A larger attack targeting civilians would yield several thousand casualties with the potential to affect millions of South Korean citizens," Brooks continued, "not to mention hundreds of thousands of U.S. citizens and nationals of other countries within the first 24 hours." 
Seoul with its 10 million inhabitants lies just 25 miles south of the demilitarized zone that separates North and South Korea. But the DPRK's tube artillery and rocket launchers could strike as far as 125 miles south of the DMZ. 
As South Korea's population grows and North Korea deploys new artillery systems that can strike farther, more and more people become vulnerable to a non-nuclear attack by Pyongyang's forces. 
32 million people live in range of North Korea's farthest-firing artillery, a 300-millimeter-diameter rocket launcher. As recently as 2000, just 27 million people were in the weapon's range.