Senior U.S. General Says Russia Poses 'Greatest Threat' to National Security

Russia now poses the greatest threat to U.S. national security and its behavior is "nothing short of alarming," Marine General Joseph Dunford, the man nominated to be the U.S. military's top officer, said Thursday.

Dunford -- who is currently the commandant of the U.S. Marine Corps -- told senators at his confirmation hearing that the Pentagon nevertheless needed to maintain some kind of military-to-military relationship with Moscow.

"Russia presents the greatest threat to our national security," Dunford, who would replace General Martin Dempsey as chairman of the US Joint Chiefs of Staff, told the Senate Armed Services Committee.

Dunford also cited China, North Korea and the Islamic State group as threats to U.S. national security.

Relations between the United States and Russia have been rocky since Moscow annexed Ukraine's Crimea region last year.

The chairman of the Joint Chiefs of Staff acts as the top military advisor to the U.S. president and the secretary of defense.