A prominent South Korean lawmaker said on Tuesday his country should consider developing nuclear weapons or bringing back a former US arsenal as a way to pressure North Korea and its ally China.

Chung Mong-Joon, a billionaire businessman who belongs to the ruling conservative New Frontier Party, said on a visit to Washington that the latest crisis with North Korea showed that diplomacy had failed with Pyongyang.

"The lesson of the Cold War is that against nuclear weapons, only nuclear weapons can hold the peace," Chung said, citing the previous long-standing nuclear stand-off between the Western allies and the Soviet bloc.

The former presidential candidate argued that South Korea has the right to withdraw from the Non-Proliferation Treaty and then to match North Korea's nuclear work step-by-step, only stopping if Pyongyang does likewise.

"It would send a clear warning that, by continuing its nuclear program, North Korea is releasing the nuclear genie in East Asia," Chung told a conference of the Carnegie Endowment for International Peace.

"North Korea -- and for that matter China as well -- should know that South Korea has this option if it persists in possessing nuclear weapons," he said, referring to Beijing's alliance with Pyongyang.

Chung, in a view endorsed by some US Republicans, said the United States also had the option to return to South Korea the nuclear weapons which it withdrew in 1991 at the end of the Cold War against the Soviet Union.

The remarks by Chung, the son of the founder of the Hyundai conglomerate, are not mainstream and few experts expect a country that has tried hard to use pop culture to give itself a friendly image to seek a nuclear arsenal.

The United States was unenthusiastic about Chung's proposal. A US official called South Korea a "committed partner" in the Non-Proliferation Treaty and said America was "steadfast" in providing a nuclear umbrella.

The US-South Korea alliance "is fully capable to deter, defend against, and respond to the threat posed to our allies, and to the United States, by North Korea," the official said on condition of anonymity.

The nuclearization of a close US ally would set back a longstanding, if repeatedly violated, principle of not allowing new nations into the nuclear club at a time when Washington is pressuring Iran over its contested program.

The United States this month took the unprecedented step of announcing a bombing test-run in South Korea by its nuclear-capable B-2 jets, in a show of force US officials said was aimed largely at quashing doubts in Seoul.

South Korea is also pressing to produce its own nuclear fuel for civilian purposes under a deal with Washington, a move resisted by the United States as it goes against a denuclearization agreement with North Korea.

The issue is expected to be on the agenda when Secretary of State John Kerry visits Seoul this weekend.

The United States stations some 28,500 troops in South Korea and around 50,000 in Japan.

While some nationalist politicians in Japan have also broached the idea of nuclear weapons, the idea is even more taboo in the only nation that has been attacked with atomic bombs.

Late South Korean dictator Park Chung-Hee -- the father of newly elected President Park Geun-Hye -- flirted with nuclear weapons in the 1970s when then US president Jimmy Carter planned to remove American troops from the peninsula.

Only North Korea has ever pulled out of the Non-Proliferation Treaty, which was signed in 1970 with an aim of preventing the spread of nuclear weapons. India, Israel and Pakistan never signed the treaty.

Chung likened South Korea's position to "a member of the gun control lobby in good standing whose neighborhood gangster just acquired assault rifles and threatens him."

"In order to buy a gun to protect himself and his family against the gangster, he now wishes to withdraw his membership temporarily," Chung said.