Obama in Turkey for summit overshadowed by Paris attacks

U.S. President Barack Obama arrived in Turkey on Sunday for a summit of world leaders that has taken on a sense of urgency following deadly Paris attacks that pushed the fight against Islamic State militants to the top of the agenda. Obama, who called the Paris attacks "an outrageous attempt to terrorize civilians" on the eve of his departure, faces the question of how the West should respond now that it has become clear that Islamic State poses a threat far beyond its militant strongholds in Sy