Barack Obama: “Working together to undermine and delegitimize ISIL's extremist ideology.”

And I will fight for that, even if I don’t always think it’s going to win.

When we choose, when we make that decision, I do believe – and there is evidence for this – that the world gets incrementally better, and that is a worthy goal and it’s worth fighting for.

It is a decision about how do we face and embrace this finite amount of time we have on the planet.

A drift towards extremism was "not inevitable