People watch a television news screen at a railway station in Seoul showing file footage of a North Korean missile launch. (Jung Yeon-je/AFP via Getty Images)

SEOUL — It seemed like a fringe idea not too long ago, but the proposal for South Korea to have its own nuclear arms is gaining steam here.

There are many reasons South Korea probably will not pursue this path. A big one: President Moon Jae-in took office in May promising a path toward denuclearization of the whole peninsula, so the chances of South Korean nuclear armament are slim.

But this debate has become a key issue after North Korea's sixth and most powerful nuclear test, carried out Sept. 3, and the controversy underscores the frustration in the South over the North’s expanding nuclear and missile program.

Throughout much of the Cold War, the United States had stationed nuclear-armed weapons in South Korea. Then, in 1991, President George H.W. Bush withdrew all tactical nuclear weapons deployed abroad, and Moscow reciprocated.

The debate over redeploying those weapons is sharply dividing South Korean politics. The main opposition party is doubling down on its calls for a redeployment of tactical nuclear weapons, buoyed by widely circulated reports from the weekend citing a senior White House official that the Trump administration isn't ruling it out as an option, as well as similar comments by Sen. John McCain (R-Ariz.), whom many here recognize as a leading U.S. voice in security matters.

“The Korean defense minister just a few days ago called for nuclear weapons to be redeployed. We had them there once in South Korea. … I think it ought to be seriously considered,” McCain said Sunday on CNN’s “State of the Union.”

Most South Koreans don’t think the North will actually start a war, according to the latest Gallup Korea poll, conducted after the Sept. 3 test.

Still, 60 percent of South Koreans in theory support nuclear weapons for their country, according to Gallup Korea. A poll by YTN, a cable news channel, in August found that 68 percent of respondents supported redeploying tactical nuclear weapons to South Korea.

The U.N. Security Council passed new sanctions on North Korea on Sept. 11 in light of North Korea's most recent nuclear tests. (Reuters)

After South Korea’s defense minister said earlier this month that it was worth reviewing a redeployment of tactical nuclear weapons, other administration officials have distanced the Blue House — South Korea's executive mansion — from the proposal. Foreign Minister Kang Kyung-wha said this week that South Korea is not considering the option and has not discussed it with Washington, but she acknowledged that public opinion is shifting toward supporting the option.

The centrist newspaper JoongAng Daily wrote in an editorial Tuesday that there is a “noticeable change in South Koreans’ attitudes about the redeployment of the nukes. Two recent polls show that the nuclear option was backed by nearly two-thirds of the people. As the debate becomes a hot potato, the Moon administration must make a wise decision.”

Kim Sung-han, dean of Korea University’s Graduate School of International Studies and a former vice foreign minister, said he fielded calls all day Tuesday from local media asking about the possibility of South Korean nuclear armament, after the United Nations voted on a watered-down version of sanctions on North Korea. The United States, South Korea and Japan had pushed for a full crude-oil embargo, which would have crippled the North Korean economy, but the U.N. resolution instead imposed a cap on oil imports to Pyongyang.

“The mainstream view is now changing in South Korea,” Kim said. “Even within the governing party, we are now hearing some of these voices who are supporting redeployment or South Korea going nuclear by herself, particularly after North Korea's sixth nuclear test.”

South Koreans are “beginning to be concerned about whether we have to continue to live under the U.S.-provided nuclear umbrella support, so they have begun to suspect the reliability of nuclear-extended deterrence provided by the United States,” Kim said.

Under previous U.S. administrations, the return of tactical nuclear armament seemed out of reach. Moon’s immediate predecessor, Park Geun-hye, reportedly requested the United States in October 2016 to redeploy the tactical weapons but was denied, South Korean media reported this week.

But now, South Koreans are wondering: Who knows what will happen under President Trump?

During the U.S. presidential election, then-candidate Trump said he would support nuclear armament of South Korea and Japan as a defensive tactic against North Korea. If Trump did so, it would represent a sharp shift in U.S. policy.

In the meantime, the ruling Minjoo Party of Korea is united with the Blue House in rejecting calls for nuclear armament and pushing for a diplomatic and political solution.

“It is undesirable for us to be seen as having no will to resolve [the standoff] politically and diplomatically anymore, amid this dispute over nuclear armament,” Choo Mi-ae, head of the Minjoo party, said at a recent meeting with senior party officials, reported Yonhap News.

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