Now, this doesn't mean we can afford to stand still. The nature of our leadership will need to change with the times. As I said the first time I came to London as President, for the G20 summit, the days are gone when Roosevelt and Churchill could sit in a room and solve the world's problems over a glass of brandy -- although I'm sure that Prime Minister Cameron would agree that some days we could both use a stiff drink. In this century, our joint leadership will require building new partnerships, adapting to new circumstances, and remaking ourselves to meet the demands of a new era.