President Barack Obama reacts as Counterterrorism chief and adviser John Brennan briefs him at the White House on the details of the shootings at Sandy Hook Elementary School in Newtown, Connecticut, December 14, 2012, in this White House handout photo released January 4, 2013. The president later said during a television interview that this was "the worst day of his Presidency." REUTERS/Peter Souza/Official White House Photo/Handout
President Barack Obama reacts as Counterterrorism chief and adviser John Brennan briefs him at the White House on the details of the shootings at Sandy Hook Elementary School in Newtown, Connecticut, December 14, 2012, in this White House handout photo released January 4, 2013. The president later said during a television interview that this was "the worst day of his Presidency." REUTERS/Peter Souza/Official White House Photo/Handout