U.S. intelligence officials have confirmed that North Korea conducted an underground nuclear test last week.
A statement from the U.S. Director of National Intelligence says radioactive material detected in air samples confirms a nuclear explosion of less than one kiloton, comparatively small for a nuclear blast.
The announcement comes as Secretary of State Condoleezza Rice prepares to leave Tuesday to visit North Korea's neighbors for talks on implementing sanctions against Pyongyang and convincing the reclusive country to return to nuclear disarmament talks.
Speaking to reporters in Washington Monday, Rice said she plans to meet with Japanese, South Korean and Chinese officials to discuss coordinating inspections of cargo going into and out of North Korea.
Chinese officials say that while troops will inspect cargo from North Korea for banned weapons materials, their forces will not stop and board North Korea ships.
China's U.N. ambassador, Wang Guangya says he believes the U.N resolution authorizing the sanctions allows for countries to carry out the inspections in different ways.
Russia's U.N. ambassador, Vitaly Churkin cautioned against a naval blockade, and warned that the interdiction of ships could enflame tensions.
U.S. intelligence officials say North Korea's nuclear test released significantly less explosive force than North Korea had expected. Officials said intelligence indicated the North Koreans predicted an explosion the equivalent of four kilotons of high explosives, but the test released less than one kiloton.
Some information for this report was provided by AFP, AP and Reuters.