What to do about Kim Jong-un, the world’s greatest showman, who is noisily threatening a nuclear war on the Korean peninsula and preparing to test a missile that could reach Guam?

Politicians and pundits are furiously debating the answer, but I’ve heard no ideas likely to persuade North Korea’s twenty-something leader to behave better. That is, until Tuesday, when a prominent South Korean legislator suggested a response that would be bitterly opposed by Washington (and Beijing and Pyongyang).

I could hear the gasps as Chung Mong-joon, a former leader of South Korea’s governing party, told the Carnegie International Nuclear Policy Conference in Washington that South Korea should build its own bomb.

“Diplomacy has failed. Persuasion has failed. Carrots ... have all failed,” Chung said. He’s correct. Time after time, U.S. and international overtures to Pyongyang (including President Obama’s) have been met with bluster, threats, and deception. When accords were signed that could have led to the normalization of U.S.-North Korean relations in return for denuclearization, the terms and the spirit were violated as North Korea continued its pursuit of weapons.

Not only did Pyongyang develop a secret program to enrich uranium, but it became a notorious proliferator, offering nuclear know-how and/or materiels to Pakistan, Syria and Iran.

South Korea, too, was bamboozled. Over the past decade, “South Korea transferred nearly $10 billion worth of cash, goods, and aid to North Korea,” Chung noted, in its effort to encourage reconciliation. Even as North Korea took the gifts, it kept developing nukes and long-range missiles.

Chung believes that North Korea never had any intention of ending its nuclear program. Given what happened to Saddam Hussein and Libya’s Moammar Gadhafi ― who halted their programs ― Kim is even less likely to end it now.

Instead, the Hermit Kingdom threatens to engulf Seoul in a “sea of flames,” using inflammatory language never heard during the U.S.-Soviet nuclear standoff. Even those who dismiss Kim’s rhetoric fear his recklessness might trigger an unintended disaster.

Chung’s conclusion: “The only thing that kept the Cold War cold was the mutual deterrence afforded by nuclear weapons.” He wants South Korea to “match North Korea’s nuclear progress step by step, while committing to stop if North Korea stops.”

The restoration of dialogue with North Korea would remain an option, but only if denuclearization topped the agenda. Success, says Chung, “will depend on whether you have a powerful deterrent. Not just sweet incentives and good intentions.”

Of course, the Obama administration opposes a South Korean bomb (as have previous administrations), and insists the U.S. nuclear umbrella is sufficient.

If South Korea begins a weapons program, it would have to withdraw from the Nuclear Non-Proliferation Treaty (it has a legal right to do so as a member in good standing). This could trigger an East Asian nuclear arms race, with Japan (or even Taiwan) following suit.

The thought of such an arms race worries the administration, but this very real prospect could provide the administration with a strategic club.

What do I mean? As Secretary of State John Kerry heads for East Asia, his main goal seems to be to persuade China to curb its North Korean ally, an approach that has never worked. The Chinese worry that any punitive cutoff of aid to North Korea might trigger its collapse, leading to a unified Korea under Seoul, with U.S. troops on their border. That prospect disturbs them far more than Kim’s nuclear threats.

True, many experts believe the Chinese are now debating North Korea policy at a higher level. The head of Carnegie’s Asia program, Doug Paal says it’s time for Kerry, on his visit to Beijing, to start a strategic dialogue over the future of the Korean peninsula. Kerry should stress that the current situation “is not sustainable,” and make the point that “the United States has no desire to put troops in the north of Korea” if the Pyongyang regime collapses.

But what if Beijing needs more prodding to see that a new approach on North Korea serves its own interests?

Here’s where Chung’s proposal could be so useful. Kerry should tell China its tolerance of Kim’s antics threatened to unleash a wave of nuclear proliferation in East Asia? He could note that, while Chung’s ideas may have limited traction now, that could quickly change.

Indeed, rather than reject Chung’s ideas, Kerry should highlight them as a preview of where the region is headed if China doesn’t rethink its Korea strategy.

“Chung is trying to add leverage to our side,” says Paal. “It won’t change the thinking in North Korea, but it might cause China to reconsider.” Which is just what everyone needs.

By Trudy Rubin

Trudy Rubin is a columnist and editorial-board member for the Philadelphia Inquirer. ― Ed.

(MCT Information Services)