SEOUL —  With North Korea primed to conduct its seventh nuclear test any time its leader, Kim Jong-un, gives the word, the confrontation between North and South Korea is spiraling toward one of its lowest levels since the Korean War.

Amid escalating rhetoric, Pyongyang, Washington, and Seoul appear to have abandoned hopes for negotiating yet another agreement for relaxing tensions, much less getting the North to give up its nuclear program. The stand-off has simmered since the first North Korean nuclear crisis in 1994, when North and South appeared on the verge of a second Korean War.

North Korea’s foreign ministry on Wednesday posted a commentary calling America “the real culprit of violating peace” and blaming Washington’s “aggressive and hegemonic Indo-Pacific strategy” for exposing the region “to the constant danger of military conflict” by waging  military exercises in  the Pacific. 

South Korea’s foreign minister, Park Jin, back from seeing Secretary of State Blinken in Washington, said North Korea was “the top policy priority for both South Korea and the U.S.” in view of concerns “about North Korea’s seventh nuclear test and its use of tactical nuclear weapons.”

Mr. Blinken is offering the mantra that America is “preparing for all contingencies” and ready “to make both short and longer-term adjustments to our military posture” — diplo-speak for threatening a military response to a North Korean missile test. Americans and Koreans, along with the International Atomic Energy Agency, say the North Koreans are done with “preparations” for the test and now everyone’s waiting for it to happen.

Kim Jong-un may have signaled his intentions with the familiar refrain that his regime has “the right of self-defense” against its enemies, notably the Americans and the South Koreans under the new conservative president, Yoon Suk-yeol, who’s promised not to “appease” Mr. Kim while working with the Americans and Japanese on mutual defense.

Mr. Kim may see American and South Korean rhetoric as not all that menacing considering that neither is talking about destroying the North’s nuclear facilities.  The fear is that North Korea,  if it refrained from responding with nukes and missiles, might still open an artillery barrage from several thousand cannon within easy range of South Korea’s most populated region, including the capital city of Seoul and the port of Incheon.

In the face of seemingly insuperable differences, the chasm between the two sides has only deepened over the years despite incredibly high hopes buoyed by the first inter-Korean summit 22 years ago, on June 15, 2000, when South Korea’s president, Kim Dae-jung, and the North Korean leader, Kim Jong-il, agreed in Pyongyang “to resolve the question of reunification independently and through the joint efforts of the Korean people.”

The most emotionally gripping aspect of the deal was agreement on reunions of members of millions of families divided by the Korean War. The media mob descended on Seoul for the first few reunions of several hundred families, selected in the South by lot and in the North apparently by their dedication and loyalty to the regime.

The confrontation worsened, however, with the breakdown in 2002 of the 1994 agreed framework under which the North was to give up its nuclear program in return for construction of two nuclear power plants to be financed largely by South Korea and Japan and shipment by the U.S. of 500,000 metric tons of heavy crude oil a year until the reactors went on line. The U.S. charged North Korea with violating the agreement by developing nuclear warheads with highly enriched uranium after the North had indeed shut down its reactor at Yongbyon under the scrutiny of the International Atomic Energy Agency.

North Korea withdrew from the nuclear non-proliferation treaty in early 2003, and Kim Jong-il ordered the North’s first two nuclear tests in October 2006 and May 2009. Kim Jong-un, taking over after his father’s death in 2011, has ordered four more nuclear tests and made sure the test site in the rugged northeastern reaches of North Korea is ready for a seventh test. In its sixth, most recent test, in September 2017, a hydrogen bomb destroyed much of a mountain, killing approximately 200 people.

Hopes shot up again, however, during the Winter Olympics in the South Korean mountain town of Pyeongchang in February 2018, when North Korea sent a team. Mr. Kim’s sister, Kim Yo-jong, showed up, much to the delight of Moon Jae-in, then South Korea’s president, who was dedicated to looking for reconciliation.

Two months later Mr. Moon met Kim Jong-un on the North-South line at Panmunjom, where the Korean War truce was signed in July 1953, and on June 12, 2018, in the brightest moment of the Trump presidency, President Trump and Mr. Kim met in Singapore. The meeting seemingly reversed the alarming trend of the previous year in which Mr. Trump at the United Nations had called Mr. Kim “rocket man” and threatened to  “totally destroy” North Korea.

Upwards of 2,000 journalists were accredited to cover the show. I was among them, confined largely to a huge press room, watching the comings and goings, hugs and smiles, on huge TV screens, while eagerly awaiting the joint statement that would emerge right after they met. Mr. Trump professed that he and Mr. Kim “fell in love,” but the statement was unbelievably anti-climactic, insipid, disappointing, and basically useless.

Far from getting the North to begin to do away with its nuclear program, the statement promised, “The United States and the DPRK (Democratic People’s Republic of Korea) will join their efforts to build a lasting and stable peace regime on the Korean Peninsula.” Meanwhile, it said, “the DPRK commits to work toward complete denuclearization of the Korean Peninsula.” The next sentence added, “The United States and DPRK commit to recovering POW/MIA remains, including immediate repatriation of those already identified.” 

I also watched three months later as a few dozen South Koreans boarded buses taking them into the North on the way to the tourist zone at the base of Mount Keumkang, a few miles above the line, for what turned out to be the last of 21 family reunions. As aging family members die off, those still well enough to see their loved ones one last time are probably not going to get the chance.

North Korea since those halcyon days has done nothing about denuclearization. The North in a blaze of publicity in July 2018 returned 55 sets of remains of the more than 7,600 Americans missing in action from the Korean War, but has not responded since then to pleas for more. The thinking is they’ve stockpiled the remains as bait in future negotiations.

The whole charade ended with the breakdown of the second summit between Messrs. Trump and Kim at Hanoi in February 2019, when Mr. Kim simply wouldn’t budge on any deal for giving up his precious nukes. I was in Hanoi for that one, too, and visited the historic Metropole Hotel where Messrs. Trump and Kim were to congratulate one another over lunch. The tables were set, but the feast was canceled.

There was, four months later, an impromptu meeting between the two at Panmunjom, when Mr. Trump, in a 40-minute conversation, suggested working-level people continue the dialogue.

The impression was that Mr. Kim had assented. Of course he had not, and that’s where we are now: at complete odds, the flowing words and promises inundated by recriminations dating from the Korean War. The difference is North Korea has ever more nukes and missiles, while America and South Korea, and Japan too, build up defenses in a long-running drama with no ending in sight.