North Korea claims it conducted a nuclear test on Monday, the second since 2006.

According to the official Korean Central News Agency, the North "successfully" conducted a nuclear test.

An official at Cheong Wa Dae said the Korea Meteorological Administration detected an artificial earthquake of 4.5 magnitude at 9:54 a.m. in Kilju, North Hamgyong Province.

President Lee Myung-bak called an emergency meeting of security ministers earlier in the morning to discuss a response.