Here’s an unsettling thought. “If North Korea conducts a fifth nuclear test, South Korea should immediately move to arm itself with nuclear capabilities,” Won Yoo-chul of the ruling Saenuri Party told Seoul’s semi-official Yonhap News Agency last week. “The existing policies are insufficient to stop the North’s technology development.”

Such sentiments are becoming commonplace. “Suppose you have a dangerous neighbor with a gun,” said Chung Mong-joon, when he was a ruling party lawmaker in 2013. “You have to take measures to protect yourself. And being a gun control advocate isn’t going to help you.”

A majority of South Koreans, living in a democratic state that looks peaceful, want the most destructive weapons on earth. Their dangerous neighbor across the Demilitarized Zone has had them for more than a decade, 54 percent of those questioned in a January Gallup Korea poll said they favored developing nuclear weapons. U.S. presidential candidate Donald Trump’s frequent calls this year for South Korea to arm itself with nukes have helped incite and ignite more demands that Seoul restart its nuclear weapons program.

And who can blame the South Koreans? Their desire to possess these devices, long predating Trump, is not just a reaction to the Republican candidate. The increasingly shrill calls for nukes are, more generally, a rebuke of continually ineffective U.S. policies seeking to contain Pyongyang, and they have implications for security far beyond North Asia.

This is not the first time that South Koreans have been thinking about a bomb of their own. Seoul secretly began a nuclear weapons program in the early 1970s during the rule of strongman Park Chung-hee, the father of the current president. The government ostensibly ended the effort, due in large measure to pressure from Washington, after Park’s assassination in 1979.

Then, in 2004 South Korea admitted it had, among other things, covertly enriched uranium from 1979 to 1981 and extracted plutonium in 1982. Both experiments with fissile material had only military applications and were clear violations of the Nuclear Non-Proliferation Treaty, the global pact that South Korea ratified in 1975.

The admissions early last decade were not entirely voluntary. Seoul made the disclosures only after the International Atomic Energy Agency, the U.N. nuclear watchdog, started asking pointed questions.

North Korea had been trying to weaponize the atom since at least the mid-1960s, and that was one of the reasons the South wanted its own bomb.

Katharine Moon, the widely followed Korea scholar at Wellesley College and Brookings, points out in comments to The Daily Beast that South Koreans are continually involved in competition with their cousins in the North—“whatever the NKs do, we will do better,” is how she characterizes the never-ending peninsular rivalry.

And Moon notes other factors: South Koreans live in “a highly militarized society,” they have “a fascination with technology and power,” they desire the status of a nuclear-armed state, and they are concerned America will not defend them.

In fact, Seoul started its first secret nuclear program as it became worried that Nixon, as the Vietnam War was ending, was leading America out of the region.

Now, the South Korean desire for a deterrent is spiking as North Korea, maybe the most destitute state today, continues bomb and missile programs while the U.S., perhaps the strongest nation in history, looks helpless to stop them. The popular attitude, therefore, is an implicit vote of no-confidence in the leadership of the world’s sole superpower, South Korea’s only protector.

Jean Lee, a Seoul-based journalist and global fellow of the Wilson Center, notes the high poll numbers for going nuke are “largely emotional” responses, and, indeed, specific nuclearization proposals from South Korea often lack logic.

For instance, Daesung Song of Seoul’s Konkuk University, while speaking at a conference in Georgetown University in June, outlined a four-stage ladder for his country. The first step is bringing back U.S. tactical nukes to Korea; second is borrowing a bomb; third is purchasing a nuke from abroad, including the U.S.; and fourth is “conducting self-production of nuclear weapons for survival.”

With regard to Song’s first step, the U.S. had tactical nuclear weapons—gravity bombs, artillery shells, and landmines—in the South until 1991, and then took them away to put them on platforms that were on, under, and over the sea.

“It makes no military sense to redeploy the tactical nuclear weapons from their hard-to-find sea, sub, and air platforms and put them into a bunker in South Korea,” Bruce Klingner of the Heritage Foundation told the Korea Times at the beginning of this month. The Washington-based analyst argues that bringing them back to the Korean peninsula would only increase the time to deploy these weapons and provide “a high value target for North Korea to preemptively attack during times of heightened tension.”

Song’s other ideas don’t work either. His concepts of renting or buying bombs are just plain silly, and developing one, his fourth stage, would be ultimately disadvantageous. True, the South, as a technical matter, could build its first nuclear device fast. South Korean military officials in 2013 said they would need only six months. That sounds about right because their country is awash in fissile material and technical expertise.

To develop an arsenal, however, would mean withdrawal from the non-proliferation treaty and accepting the global condemnation and punishment that would follow. Won Yoo-chul, the Saenuri figure, notes that North Korea withdrew from that treaty, but that is not a smart comparison. The North was and remains an isolated state and does not care if it is shunned, but South Korea is highly integrated into the international system and needs friends. The South, therefore, would lose its coveted place in global councils, and, more to the point, the sanctions that would inevitably follow could severely damage its export-dependent economy, now ranked the world’s 11th largest.

Plus, the U.S. would probably walk away from the South, making the country far more vulnerable than it is today. An already isolationist American public would ask why 28,500 Americans troops now in the South are needed when Seoul had its own nuclear deterrent. And this is not a theoretical concern, because Mr. Trump has questioned America’s pledge to defend South Korea and has implied there would be no need for the U.S. to stand with a nuked-up South.

Some South Koreans point out the U.S. has a strong friendship with nuclear-armed Israel, but the situations are different. Israel is not a signatory of the nonproliferation treaty, the U.S. does not base troops there, and Israel does not especially need outside help. South Korea, however, relies on the American “tripwire” force and the cooperation of American ally Japan.

Moreover, Seoul relies on American nukes. “South Korea already has the backing of the best nuclear force on the planet with its ally, the U.S.,” notes South Korea-based Robert Collins, who works closely with American forces on the Korean peninsula, in an e-mail to The Daily Beast.

Will the calls for Seoul to build the bomb eventually fade? The Wilson Center’s Jean Lee notes in an e-mail to The Daily Beast that support for nuclearization is weakest among those in younger age cohorts. “They clearly feel more removed from the issue than their parents and grandparents,” she notes of the 19-to-29-year-olds.

Yet South Korea’s desire to possess its own deterrent is likely to grow in the years immediately ahead. Sung-Yoon Lee of the Fletcher School of Tufts University tells The Daily Beast that the “nuclear taboo” is not that strong in the South.

And there is another issue. “Popular passions ebb and flow, yes,” he writes, “however the ominous trajectory of Pyongyang’s growing nuclear threat over the past quarter century can only impel South Korea to reassess its nuclear posture, perhaps as soon as some time in the coming decade.”

Washington, therefore, cannot maintain ineffective North Korean policies over the course of decades and hope to maintain a strong alliance with Seoul. And it is not only the South Koreans who are watching.

Unfortunately, the lack of confidence in Washington is increasingly shared across East Asia. American leadership is failing at a critical moment, dismaying friends, emboldening aggressors—and laying the groundwork for fast proliferation.

If South Korea goes nuke, Collins anticipates other nations will do the same. So in rapid fashion expect states to “break out” from the global non-proliferation treaty, spreading the bomb around the region, and probably beyond.