The thing is, he says “we will not be intimidated,” but the American government and military establishment is already intimidated, and Obama himself has been a chief agent of that intimidation. He shows that he is intimidated when he makes the wild and ridiculous claim that the Islamic State has nothing to do with Islam, and forbids intelligence and law enforcement officials to study the motives and goals of the jihad terrorists. This is intimidation on a massive scale, rendering his words here utterly hollow.
“Remarks by President Obama and President Ilves of Estonia in Joint Press Conference,” White House, September 3, 2014 (thanks to Jerk Chicken):
Whatever these murderers think they’ll achieve by killing innocent Americans like Steven, they have already failed. They have failed because, like people around the world, Americans are repulsed by their barbarism. We will not be intimidated. Their horrific acts only unite us as a country and stiffen our resolve to take the fight against these terrorists. And those who make the mistake of harming Americans will learn that we will not forget, and that our reach is long and that justice will be served.