marnlger gater is at the white house with early details, major? >> good evening, the president will describe the san bernardino attacks as an act of terrorism and will shed light on the fact that this attack was of a kind long feared. one not connected to an organized terrorist conspiracy but terrifying and lethal just the same. >> reporter: president obama decided to address the nation after meeting saturday with his national security team. the challenge, reassure a jittery nation his administration understands and can confront the evolving terrorist threat here at home. investigators are examining how virtually untraceable radicalization lead to the san bernardino plot. one hatched and then hidden from friends, family and law enforcement. >> this is what the president said in his weekly address saturday. >> it is entirely possible that these two attackers were radicalized to commit this act of terror. and if so it would underscore a threat we've been focused on for years. the danger of people succumbing to violent extremist ideologies. >> report