President Bush has declined to say whether he has information about any planned North Korean nuclear test.
Mr. Bush told reporters Friday that such a question is hypothetical. He also said he will not divulge any intelligence information. He said any such test would be a reminder to North Korea's neighbors that the country poses a threat.
A U.S. news organization, ABC News, on Thursday quoted anonymous U.S. officials as saying Pyongyang may be planning an underground test. They cited recent activity at a suspected nuclear test facility in North Korea. The United States relies heavily on satellite images to monitor North Korean activities.
South Korea's top official on relations with North Korea, Unification Minister Lee Jong-seok, told lawmakers Friday that the South Korean government has no confirmed evidence that North Korea is pursuing a nuclear test.
Last month, North Korea defied international warnings and test-fired seven ballistic missiles over the Sea of Japan.
North Korea's neighbors and the United States have unsuccessfully lobbied Pyongyang to return to nuclear disarmament talks.
Some information for this report was provided by AFP and Reuters.