U.S. intelligence authorities reportedly held a special forum in May to assess the rising nuclear threat from North Korea.

According to the Wall Street Journal(WSJ) on Wednesday, dozens of U.S. intelligence officials, military officers and security analysts held a two-day meeting from May 23 at the headquarters of U.S. Strategic Command in Omaha, Nebraska.

The paper said the previously unreported forum was hosted by the Office of the Director of National Intelligence and the Defense Intelligence Agency.

The WSJ said the event was the first at the headquarters of U.S. Strategic Command to focus solely on North Korea's nuclear program.

Strategic Command, the arm of the Pentagon tasked with deterring the U.S.' rivals, usually holds separate forums on the nuclear programs of Russia and China once a year.

U.S. intelligence authorities are reportedly paying attention to the advancing nuclear capabilities of North Korea.

Some of the participants reportedly expressed concern that in event of armed conflict, North Korean leader Kim Jong-un may use small nuclear weapons in order to force South Korea and the U.S. to make concessions.