The Senate took part in a rare White House briefing on Wednesday to hear what senior leaders described as "an urgent national security threat" posed by North Korea's nuclear and missile programs.

The hour-long secret session for all senators was held at the Eisenhower Executive Office Building, next to the White House, and included a brief appearance from President Trump who made short, introductory remarks.

Marine Corps Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, also took part in the session. His presence is an indication that military options for dealing with North Korea likely were discussed.

New steps by the administration will include the imposition of additional economic sanctions.