Pyongyang conducts a nuclear test, Seoul, Tokyo, and Washington promise to make Pyongyang "learn of its fault."

In order to ensure that North Korea understands it has made a clear "wrong decision," South Korea, Japan, and the United States have committed to work together to take severe action against the dictatorship if it performs a nuclear test, Seoul's security director said on Thursday (US time).

After meeting with his colleagues from the US and Japan, South Korea's national security adviser Kim Sung-han said that the thr....