The North Korean government claimed to have carried out a successful nuclear test May 25. Initial reports from South Korea suggest the detonation, originating near Kilju in North Korea — site of the country's first nuclear test in 2006 — registered 4.5 on the Richter scale. North Korea's first nuclear test created an explosion that registered 3.6 on the Richter scale. North Korea warned in late April that it would carry out a second nuclear test, along with additional tests of its long-range Taepodong missile (which the North Koreans call the “Unha,” or “Galaxy,” missile — which it used as a satellite launch vehicle, not a ballistic missile), in response to U.N. censure of its attempted satellite launch earlier that month.