Some US journalist came up to me and said: 'How can you say this about President Bush?' Well, I think what I said then was quite mild. I actually think that Bush is the greatest threat to life on this planet that we've most probably ever seen. The policies he is initiating will doom us to extinction.
As quoted in "Livingstone says Bush is 'greatest threat to life on planet'" by Nigel Morris, in The Independent (18 November 2003), p. 5.