US Lt. Gen. Curtis Scaparotti, the deputy commander of American forces in Afghanistan, told reporters traveling with Panetta in Kabul that the driver was an interpreter working for the foreign forces.
The man apparently had a container of fuel in the car, which ignited during the crash Wednesday at the British airfield in Helmand province in southern Afghanistan.
"There was a puff of smoke and he came out engulfed in flames," Scaparotti said. He said the truck was headed toward a group of US Marines assembled at the ramp.
"My personal opinion, yes, he had an intent to do harm," Scaparotti said.
But he said he did not think the incident was related to Panetta's arrival because it would have been difficult to know which plane the defense secretary was aboard.
No one in Panetta's party was hurt. The defense secretary was told about the incident after he got off the aircraft.
Authorities were not able to talk to or get any information from the driver before he died.
A US military official said a British soldier was injured when he tried to stop the driver from stealing the truck on the base. The Afghan man hit the British soldier with the truck as he was driving away.