"Frantic efforts are under way in Washington and London to find an exit strategy for Iraq as a renewed surge in violence led George Bush to admit yesterday that tactics there might need to change. Diplomats and politicians in both capitals are desperately reviewing and debating options that were once regarded as unthinkable. The review was given added urgency yesterday when 800 gunmen, thought to be part of the Mahdi army militia, ran amok in Amara, a town transferred by the British to Iraqi control two months ago."