In what appeared to be the first case of U.S. troops being hit by "friendly fire" from a drone aircraft, two American servicemen were killed by a Hellfire missile after apparently being mistaken for insurgents moving to attack another group of Marines in southern Afghanistan.
A Predator drone fired the missile that killed a Marine and a Navy medic in Helmand province last week, according to two Pentagon officials.
Drones have been involved in airstrikes that accidentally killed Afghan and Pakistani civilians since the U.S. began using them in the region a decade ago, becoming a flashpoint for anti-American sentiment. But until now, no U.S. service members have been reported killed by an unmanned Air Force aircraft in error.
Dozens of Predators and more heavily armed Reaper drones fly every day over Afghanistan, operated remotely by pilots at air bases in the United States. Cameras aboard the drones also provide live video feeds to ground combat units, which have come to rely on the drones surveillance as well as for air cover.
"With increased [drone] usage, there are going to be more incidents like this," said Louis Tucker, the former staff director of the Senate Intelligence Committee and a Navy Seal in the reserves. "People have an expectation that because it's automated, there won't be mistakes, and that's never the case in war."
The missile strike occurred about 9:30 a.m. last Wednesday near the crossroads town of Sangin. The former insurgent stronghold has seen a resurgence of clashes in recent weeks between Marines and Taliban fighters, the officials said.
Marine Staff Sgt. Jeremy D. Smith of Arlington, Texas, and Seaman Benjamin D. Rast of Niles, Mich., were hit as they moved on foot in a group trying to reach other Marines who had been pinned down by insurgent gunfire.
One Pentagon official said the Marines called in the airstrike when they saw images on the video feed of unknown men heading toward them. It wasn't immediately clear why the rescue team headed their way was not clearly identified.
The video feeds sometimes provide blurry or unclear images of conditions on the ground, making it hard for screeners responsible for searching the video for possible targets to always understand what they are seeing.
In a statement, the US.-led International Security Assistance Force in Kabul confirmed that two service members had been killed in a coalition strike but did not disclose the role played by the Predator.
"An ISAF Joint Command incident assessment team is looking into the incident," the statement said. "A formal investigation will determine the circumstances that led to the incident."
Smith and Rast were with the 1st Battalion, 23rd Marine Regiment, a reservist unit based in Houston that deployed to Afghanistan last month on a seven-month rotation.
Rast's father, Robert, told a television station in South Bend, Ind. , that the Pentagon had informed him that his son had been killed by a Hellfire missile.
Rast, 23, joined the Navy about a year ago and was stationed in San Diego at the Naval Medical Center before being assigned as a medic to the Marine regiment prior to its deployment to Afghanistan last month.
Robert Rast told the Houston Chronicle that he had talked to his son about going to Afghanistan around Christmas.
"I said, 'Son, I won't lie to you. I'm worried about you and your deployment. What if something happens to you? What will I say to everybody.' He said, 'Dad, just tell them I wanted to be on the front lines covering the guy on my right and covering the guy on my left…You won't have to say any more.'"
Smith, 26, joined the Marines in 2003 and had served three tours in Iraq. He joined the reserves after leaving active duty and was called up to Afghanistan.
In a statement to the Chronicle, Smith's family said, "The Bible says that we are to run the race that is set before us. Jeremy did that even though it was a difficult race… As a leader with experience, he felt that he needed to go back, to ensure that his guys made it home safely. That is why he did four tours."
Senior U.S. Air Force officers say that mistakes involving drones are rare because special cameras and sensors enable drones to observe potential targets far longer and with more precision than conventional aircraft and other surveillance platforms.
But with an increasing number of drones flying in Afghanistan, the possibility of mistaken airstrikes also has increased.
In one instance last February in Oruzgan Province, at least 15 men were killed and 12 people were wounded, including a woman and three children, after a Predator drone crew mistook them for insurgents. In that case, the missile strikes were carried out by attack helicopters