US, South Korea to respond swiftly in case of North Korea nuclear test: Official

US Deputy Secretary of State Wendy Sherman said on Tuesday there would be a strong and clear response from the United States, South Korea and the world if North Korea conducts a nuclear test.

“Any nuclear test would be in complete violation of UN Security Council resolutions (and) there would be a swift and forceful response to such a test … I believe that not only ROK and United States and Japan but the entire world will respond in a strong and clear manner,” she told reporters after talks with her South Korean counterpart, Cho Hyun-dong, in Seoul. ROK is the Republic of Korea, South Korea’s official name.

“We are prepared and … we will continue our trilateral discussion (with South Korea and Japan) tomorrow,” Sherman added.

Her remarks comes after South Korea and U.S. forces fired eight surface-to-surface missiles early on Monday off South Korea’s east coast in response to a barrage of short-range ballistic missiles launched by North Korea on Sunday.

Meanwhile, the International Atomic Energy Agency chief Rafael Grossi later on Monday said North Korean building work expanding key facilities at its main nuclear site at Yongbyon is advancing.