Yet on Thursday , all of the world leaders who have arrived here for the relief effort -- Secretary of State Colin L. Powell ; Prime Ministers John Howard of Australia , Wen Jiabao of China and Junichiro Koizumi of Japan ; Foreign Secretary Jack Straw of Britain ; Secretary General Kofi Annan of the United Nations ; the president of the World Bank , James D. Wolfensohn ; and a score of aides , ambassadors and senior officials -- were gathered in a conference center here in the shadows of the Hilton .