WASHINGTON (AFP) - An explosion rocked a joint Afghan-US combat post in eastern Afghanistan Thursday, injuring several US troops, the Pentagon said, but it was not immediately clear if it was an attack. An explosion occurred at a joint ANSF/ISAF combat outpost in Paktiya province, eastern Afghanistan this evening, the US military said in a statement. Several ISAF service members from the United States were injured. There were no reported fatalities to ISAF or ANSF personnel, it said.