Russian news agencies cited on Monday Defense Ministry officials as confirming that North Korea carried out a nuclear test.
State-run RIA-Novosti quoted an unidentified ministry official as saying North Korea tested a nuclear device in the northeastern part of the country.
ITAR-Tass and Interfax also quote ministry officials as saying Russian facilities detected a nuclear test.
ITAR-Tass quotes an unnamed official as saying Monday that the device had a force of about 20 kilotons.
Russian Defense Ministry and Foreign Ministry officials declined immediate comment.