Can a war ever be justified?

A Few days ago, President Obama accepted the Peace Nobel by the Norweigan Nobel Committee in Oslo, at a time when America is fighting two wars- first, a morally justified one against global terror in Afghanistan & the other, a more debatable one in Iraq. He himself acknowledged the irony but that is not what makes it so unique. What he really did was that Obama answered an annoying question that seems to be hovering in every intelligible human mind and more importantly a question that the world has been asking America since their invasion of Iraq- Is a war ever justified? Is it really necessary to kill or risk getting killed to obtain peace? To answer this question, Obama mentioned the lines of Mandela," a war no matter how justified promises human tragedy." For war never is, was or will be right solution to attain peace, but some wars have to be fought to protect the right causes, right fundamentals & the right people. There is evil in the world & till it exists, we all have to come together to fight it...