Defense Secretary Robert Gates says the nations fighting in Afghanistan have until roughly the end of this year to show the war is turning around.
Otherwise, Gates says, people in the United States and elsewhere won't support the effort.
He says war commander General Stanley McChrystal is confident he can show progress in that time.
Gates spoke in London following strategy sessions with the United States' closest ally in Afghanistan.
Public support for the eight-year war is dropping in both the U.S. and Britain.