North Korea only recently developed the ability to threaten the U.S., but the rogue regime’s dark shadow has lingered over its southern neighbor for many years.

Before the North acquired nuclear weapons, the Pentagon estimated that North Korea could kill as many as 20,000 South Koreans a day in a renewed conflict on the Korean Peninsula, the Los Angeles Times reported, citing information provided by retired U.S. Air Force Brigadier General Rob Givens.

Experts suggest that this figure is realistic, especially if a conflict starts with little or no warning.

“The scale of an artillery barrage [from the North] initially would be pretty massive. You’d be looking at several thousand rockets and artillery pieces being fired over the course of several hours,” Ian Williams, the associate director of the Missile Defense Project at the Center for Strategic and International Studies, explained to CNBC.

“When I was in government, when we ran war games, the estimates were hundreds of thousands of casualties, and that was before we thought North Korea had nuclear weapons,” Bruce Klingner, the former chief of the Central Intelligence Agency’s Korea branch and now a senior research fellow for Northeast Asia at the Heritage Foundation’s Asian Studies Center, previously told The Daily Caller News Foundation.

With North Korea’s improved capabilities, which include reliable, high-precision short-range Scud missiles capable of being armed with nuclear, biological, chemical, and conventional payloads, North Korea could potentially rain down significant destruction on the South. (RELATED: North Korea’s Got A New ‘Ultra-Precision’ Missile)

South Korea is in the process of boosting its indigenous missile defense capabilities while relying on the U.S. for defense through elite antimissile systems like the Terminal High Altitude Area Defense (THAAD) system, which has a perfect test record and is operationally ready to intercept missiles over South Korea if necessary.

The North is taking steps to counter these defenses, though, improving the effectiveness of its older short-range missiles with terminal maneuverability upgrades. Both the KN-18 and KN-21, modified versions of the decades-old Scud-C and Scud-B missiles, are believed to have this ability, which would allow these missiles to skirt enemy defenses. (RELATED: North Korea Has Been Secretly Making Its Older Missiles Deadlier)

There is also the nuclear component. North Korea successfully tested a suspected staged thermonuclear weapon — a hydrogen bomb — earlier this month, showing the world just how far the rogue regime’s nuclear program has progressed. While the warhead is designed for North Korea’s Hwasong-14 (KN-20) intercontinental ballistic missile, it is very likely that North Korea’s short-range missiles could deliver a substantial nuclear payload to targets in South Korea.

It is unclear exactly how North Korea might strike, or even where. The North could target bases, as well as population centers, such as Seoul, which is located only 35 miles from the border and is home to a metropolitan population of roughly 25 million people.

“The North Koreans say both,” Jeffrey Lewis, the director of the East Asia Nonproliferation Program in the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies, previously explained to TheDCNF. “They hope the shock will cause us to recoil, and if it does not, they hope the damage slows us down.” (RELATED: What Would Happen If Kim Jong Un Launched A Nuclear Strike?)

North Korea has, on more than one occasion, threatened to turn South Korea into a “sea of fire.”

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