A suicide bomber detonated an explosives-laden car near a NATO base in southern Afghanistan on Thursday soon after a visit by U.S. Defense Secretary Leon Panetta, killing two people and wounding 16, Afghan and NATO officials said.
His spokesman said there was no indication Panetta was the target. Panetta had visited Kandahar Air Base just hours before the attack, meeting U.S. troops before the Christmas holiday.
"The attack occurred after the Secretary returned to Kabul," spokesman George Little said.
Three foreign soldiers were among the wounded.
Panetta was due to meet Afghan President Hamid Karzai later on Thursday as the United States weighs how big a fighting force to keep in the country after the NATO mission ends in 2014.
A trip to Afghanistan by Panetta in March was overshadowed by an attack on his welcoming party by an Afghan translator, who drove a vehicle onto the runway and apparently tried to detonate the vehicle.
Panetta met commanders in Kabul to finalize options for U.S. President Barack Obama on how many troops to keep in Afghanistan after the NATO mission ends.
He has not disclosed how large a force he believes will be needed but one U.S. official has said figures as low as 6,000 U.S. troops were under consideration, compared to 68,000 now.