They also know that bluster spills over into real violence periodically. Seoul's inhabitants live within artillery range of North Korea, but life goes on.
Across the water, Japan's government has launched a public information campaign about how to prepare for a ballistic missile attack, which the Prime Minister has warned could include chemical weapons.
Farther away still, in Washington, war talk is more prevalent. "All options" remain on the table, including preventive strikes to prevent North Korea from developing an Inter-continental Ballistic Missile
What explains this inverse ripple effect? The primary factor is North Korea's own efforts to develop the capability to project mass destruction in ever-increasing concentric circles, with the ultimate goal of a nuclear-tipped ICBM that can hit the US -- something that only Russia and China can do at present.
Following on from North Korea's latest series of rocket trials, a cornucopia of ballistic missiles paraded in Pyongyang on April 15 -- including ICBM launchers -- was a bold signal of intent to do just that. They are not there yet, but practice makes perfect. There is a strong chance Pyongyang will realize this capability within Donald Trump's time as president.
As the ultimate guarantee of regime survival, it is unrealistic to expect that Kim Jong Un can be persuaded to deal his nuclear ace out of the pack.
The nuclear ICBM is the incendiary game-changer that explains why the US has gone to deliberate lengths to confront North Korea since Trump took office. To be sure, North Korea's nuclear missile program would feature near the top of any White House security watch-list. But it's not clear the Trump administration has developed a coherent strategy to counter it yet.
As the State Department's former North Korea point man Christopher Hill said recently, it's as if the Trump administration is trying to out-North Korean the North Koreans. Matching brinkmanship with brinkmanship.
Yet for my money, we are in a phony war phase. If there's an underlying motive to Washington's increased belligerence, including the accumulation of strike assets around the Korean Peninsula, it is to get the Chinese sufficiently rattled that they become serious about sanctions beyond tokenistic enforcement. If not, then the US will get serious about sanctioning Chinese entities doing business with North Korea. And if that fails -- and only then -- will we see a genuine momentum toward US military action.
To be crystal clear, there are no easy or risk-free options for that scenario. This isn't Syria. A second Korean War would be a bloody and unpredictable affair. Recent US interventions in the Middle East would pale by comparison. It is, however, possible that an ICBM test, intercepted over the water, or even destroyed on the ground would not automatically trigger the North Korean escalation that is frequently assumed.
Given its overall inferiority, North Korea's military relies on rapid escalation to deter US and South Korean invasion. That is likely to include use of nuclear weapons to target US bases in the region, in the early stage of any conflict. The North Koreans, Kim Jong Un included, are calculating and rational survivalists. Threat is their leverage.
But brinkmanship also relies on knowing when to pull back. The absence of a nuclear test in recent weeks suggests Kim is calibrating his demonstrations of defiance. He presided over a mass artillery drill to mark a major military anniversary this week, but no more.
Kim Jong Un now faces a growing risk: not simply an emboldened US under Trump, but its estranged ally, China, applying the economic thumbscrews.
We should never forget that Kim is also looking over his shoulder at his generals, whose material wants he must continue to please, and who likely have no appetite to fight a conventional or nuclear war that will spell their demise. The internal enemy is always trickiest to deal with.
Trump and Kim have more in common than many realize. Neither wants a war. But there is still a risk they will box each other in, or else Kim concludes Trump is bluffing and oversteps the mark. That would be the most destabilizing outcome from the current episode.
I do not believe that the US is about to launch strikes any time soon. My guess is that it will give China some months to produce results, an approach that could drift on for longer if the North Koreans continue to play it safe. Unfortunately, that's not really in either man's nature.