Regarding the "War on Terror", Obama recently said:“This war, like all wars, must end. That’s what history advises. That’s what our democracy demands.”
He's right that wars end, but he's not right as to why.
Wars end when both sides stop fighting. Usually that's because one side totally defeats the other. It only takes one side to start a war, and it only takes one side to keep a war going. If people want to pursue certain ends through the aggressive use of force, then they're going to do that until they decide not to. Jonah Goldberg sums this up quite nicely in his piece: Our Enemies Gets a Vote.
Obama can say that the "War on Terror" is over as much as he wants to. He can genuninely wish for it to be over. Heck, I wish that it were over. The only problem with that is that the Islamic radicals get a vote. They get to decide when it's over, and so far, I'm not seeing any signs that they are giving up.
Wars continue until both sides agree to stop. No war in the history of the world has totally ended until both sides agreed that the war was over. Usually, the best way to convince the other side to stop fighting is to destroy their forces. That's the lesson of history.