[walking around the TARDIS console] The end of your life… has already begun. There is a last place you will ever go. The last door you will ever walk through. A last sight you will ever see. And every step you ever take… is moving you closer. The end of the world is a billion, billion tiny moments. And somewhere unnoticed, in silence or in darkness… it has already begun.
It could have chosen anywhere on this planet. It chose to sit on the strategic intersection of the three most powerful armies on Earth. So what it's doing, Colonel, is sending us a message.