In the past, South Korea has flirted with developing a nuclear weapon but was successfully talked out of it by the United States. But that was decades ago. With the threat from North Korea growing and new questions being raised about how reliable an ally President Donald Trump is, what had been a fringe-issue for South Korea's far-right camp has in the last year become an acceptable prospect for the conservative opposition and over half of the country's population.
South Korea currently has a liberal president, Moon Jae-in, who has adopted an anti-nuclear policy and pushed for renewed diplomacy with Pyongyang. But if talks with the North fail, as many expect they will, and South Korean liberals are voted out of office, the conservatives will return to power. If and when that day happens, a critical question will be if they abandon or moderate their current support for a domestic "nuclear weapons option."
Much of how that question is answered can be shaped in the short-term by the United States, but only if policymakers in Washington pay attention and respond to the under-the-radar developments happening in South Korea.