Following a U.S. intelligence report revealing unexpectedly rapid advances in North Korea’s nuclear-missile program, President Trump has spent the last several weeks mulling military action to destroy dictator Kim Jong-un’s ability to threaten the United States and its allies.
But a preemptive strike on the hermit kingdom’s high-profile nuclear program could lead to the use of the country’s other weapons of mass destruction. North Korea possesses one of the largest chemical arsenals on the planet: an estimated 2,500 to 5,000 tons of toxic agents. And experts say a war on the Korean peninsula would quickly see the region around South Korea’s capital city Seoul—home to around 25 million people—inundated with vast plumes of poison gas.
Intelligence agencies believe that North Korea began developing these deadly weapons decades ago, although Kim Jong-un denies his country possesses chemical agents. Some experts believe North Korean military advisers are closely involved in chemical attacks that Syrian dictator Bashar al-Assad conducted against his own people, which provided valuable operational knowledge of North Korea’s capabilities. Experts are also disturbed by Kim Jong-un’s brazen public assassination of his half-brother using the nerve agent VX, saying it demonstrates the regime’s willingness to use deadly toxins.
“I think if people paid more attention to the chemical side, they’d be less inclined to talk about preemption and going first against North Korea,” said Greg Koblentz, a researcher of weapons of mass destruction at George Mason University.
The exact composition and size of North Korea’s chemical arsenal is unclear, but it’s believed to include everything from antiquated chlorine gas all the way up to sarin, VX, and other highly lethal nerve agents. These weapons are distributed at facilities across the country, often tucked away in underground bunkers or other sites unknown to U.S. and allied intelligence.
The weapons are also deployed along the armistice line, which sits just 35 miles north of Seoul. Bruce Bechtol, a former Defense Intelligence Agency officer and an expert on North Korea, says the Pentagon and South Korean intelligence believe as many as one in five of the hundreds of long-range artillery pieces now trained on Seoul are loaded with chemical munitions. Should war break out, Bechtol paints a horrifying tableau of skyscrapers crumbling under conventional artillery while rockets and shells wreathe the devastation with toxic clouds.
Unlike nuclear weapons—which some believe the North would use only in a last-ditch, scorched-earth effort—chemical weapons would almost certainly be deployed as soon as hostilities broke out. “I think we should expect that [North Korea] will use chemical weapons in the early part of any barrage against Seoul,” said Bechtol. “That would create a situation to their advantage. They’d have the South panicked—at least the civilian part of the South panicked—which hurts logistical flow, which hurts the flow of forces.”
David Maxwell, the associate director of the Center for Security Studies at Georgetown University and a former U.S. Army colonel with extensive experience on the Korean peninsula, called chemical munitions an indispensable part of the North’s wartime strategy. “They’ve got to win, and they’ve got to win quickly,” said Maxwell. “So they’ve got to bring to bear all their capabilities to be able to be successful as quickly as possible. That’s why I think they would use chemical weapons.”
In addition to the assault on Seoul, Maxwell says the North is also likely to saturate airbases and ports on the Korean peninsula with sustained chemical-weapons fire. Until their artillery batteries are taken out by airpower or counter-artillery fire—a process likely to take at least several days—those attacks could stop allied aircraft from taking off and prevent reinforcement-laden ships from docking until cleanup crews could safely scrub the facilities.
The North would also target the front line directly, hoping to pin down U.S. and South Korean forces in a haze of poisonous fumes while its soldiers attempt to break through the defenses lining the demilitarized zone. “That means degraded operations, as forces have to wear chemical-protective gear,” Maxwell said. “That makes it harder to conduct routine operations. And so the threat of it is significant even if they don’t use it.”
Bechtol and Maxwell believe North Korea is providing advice and material support to the Syrian government in its civil war, particularly when it comes to its chemical operations. “They’ve seen what the most effective weapons platforms are; they’ve been able to look at time and distance and judge how these platforms would be used,” Bechtol said. “So [Syria]’s been the perfect training ground for North Korea for any conflict they would be in.”
Maxwell worries that the U.S. government may be underestimating the importance of North Korea’s activities in Syria. “We should certainly be observing for and preventing the North Korean military in Syria from learning lessons,” he said. “Unfortunately, the way we think from a national security perspective, we think geographically, maybe regionally.”
There’s also the ominous assassination of Kim Jong-un’s half-brother in a Malaysian airport last February using VX nerve agent. “The fact that the North used VX—that is a pretty significant event,” said Koblentz. “Because that confirmed not only that the North has chemical weapons, but that they have one of the most advanced type of chemical weapons.”
There are limits to the reach of North Korea’s chemical program. While long-range missiles could theoretically be tipped with toxins, the payload would have to be very small for the projectiles to make it to the mainland United States, Hawaii, Guam, or even nearby Japan. That likely limits the large-scale use of chemical munitions to the Korean peninsula. Experts also say that U.S. and South Korean forces are well-trained and equipped for chemical strikes, and would fight through the onslaught and secure or destroy the North’s chemical stockpiles with all due haste.
But that’s small comfort for South Korean civilians, thousands of whom would be expected to die painful, toxin-induced deaths in the event of hostilities between the United States and North Korea. While U.S. Patriot missile batteries and the newly deployed Terminal High Altitude Area Defense (THAAD) system are expected to ward off at least some of the missile attacks launched into the South, they’ll do nothing to prevent thousands of shells and rockets—both conventional and chemical-tipped—from raining down on Seoul in the conflict’s opening days.
“We have to keep in mind that we will see a scale of death and destruction in the South that we have not seen since the armistice in 1953,” Maxwell said.