4 Americans die in Afghanistan blast

Four more American troops died in a bombing in southern Afghanistan, the U.S. military said Friday, as a U.N.-backed panel completed most of its investigation into whether the level of fraud in the August presidential election would require a runoff.

Afghanistan's ambassador to the United States says he expects a second round vote will be required.

Rising death tolls and the political crisis brought on by a fraud-marred election have prompted the Obama administration to review its entire Afghanistan war strategy.

Two of the U.S. service members were killed instantly in the Thursday blast and two others died of their wounds, the U.S. said in a …