North Korea is raising the stakes and the risks in the nuclear confrontation with Seoul amid debate among Americans and South Koreans over whether the South should go nuclear.

A new light water-nuclear reactor at the North’s main nuclear complex, together with shrill rhetoric from the North’s leader, Kim Jong-un, marks the beginning of what looks like a dangerous new era of threats and counter-threats on the Korean peninsula.

Adding to tensions, Russia is providing much needed expertise for the North’s latest model intercontinental ballistic missile, the Hwasong 18, that should be capable of carrying a nuclear warhead to targets in North America.

“The game has changed significantly,” according to a former marine intelligence analyst and author of five books on North Korea’s armed forces, Bruce Bechtol. “We are likely to see large-scale technical support and military assistance from the Russians.”

As underlying factors, Mr. Bechtol cites “Russia’s desperation to get large amounts of military equipment and ammunition from the North Koreans, and Kim Jong-un’s insatiable desire to continue to modernize and upgrade his ballistic missile force.”

Add the North’s mounting nuclear power to the prowess of its missiles, including ICBMs and short-to-mid-range models for hitting targets anywhere in South Korea and most of Japan, and you have a combustible mix that could explode as tensions worsen.

For that reason many South Koreans believe the South has no choice but to develop its own nukes — something Washington has always opposed while promising the security of the American “nuclear umbrella.”

“South Korea has no other option than developing its own nuclear capability in the near future,” a one-time official with the South’s National Intelligence Service, now a lawyer in Pennsylvania, Kim Kisam, told the Sun. “No other choice at all,” he added. “Period.”

South Korea’s president, Yoon Suk-yeol, in meetings with President Biden at Washington and then with Mr. Biden and Japan’s prime minister, Fumio Kishida, at Camp David, has agreed on frequent consultations while accepting his promise of a firm response.

“The US government does not want South Korea to develop nuclear weapons,” Mr. Bechtol told The Sun. “Recent agreements did not call for rebasing US nuclear weapons in South Korea.  The US has already reaffirmed its strong commitment to the nuclear umbrella and extended deterrence.”

Mr. Yoon, however, appears uneasy about such assurances, as was evident when he visited South Korean troops near the demilitarized zone between the two Koreas.

“North Korea is the only country in the world that specifies invasion and preemptive nuclear use in its constitution,” South Korea’s Yonhap News quoted him as saying.  “They can initiate provocations at any time.” 

Mr. Yoon’s advice to the troops: “Act first, report later. If provoked, please immediately retaliate, and report afterward. I ask you to decisively crush the enemy’s will to provoke on the spot.”

Those words are not mere rhetoric. Just this past week, Mr. Yoon ordered exercises of his military, police and civil defense forces simulating responses to North Korean drone attacks. In recent months, he’s approved numerous exercises with American troops — and with Japanese naval and air forces in displays just short of alliance with Korea’s one-tine colonial ruler.

For now, veteran American analysts doubt if a South Korean nuclear program is in the cards despite the undoubted brilliance of physicists and engineers at the Korea Atomic Energy Institute and the success of 26  reactors that supply one-third of the South’s electricity.

A long-time Korea analyst at the Heritage Foundation, Bruce Klingner, noting that Mr. Yoon a year ago spoke of “potentially going down the nuclear path,” believes Mr. Biden has managed to allay concerns.

“While outside experts may continue to advocate for an indigenous program,” he told the Sun, “the U.S. and South Korea have repeatedly stated there will be no South Korean nuclear program nor redeployment of U.S. tactical nuclear weapons into South Korea.”

A retired army colonel, David Maxwell, now vice president of the Center for Asia Pacific Strategy, sees no reason for the South to develop its own nuclear weapons.

For one thing, he told the Sun, Mr. Kim “is unlikely to be deterred by anything South Korea does” — and “no one in South Korea can describe with any intellectual rigor what will deter him.”

Colonel Maxwell asked, too, whether “possession of nuclear weapons with no concept for employment, with no deterrent capability” is “worth risking the alliance with the presence of U.S. troops and extended deterrence?”

The news from Pyongyang, though, is disturbing. As a State Department spokesperson told Yonhap, the North has  been  “characterizing some of its missile launches and other military activities as trial runs for the use of tactical nuclear weapons.”