WASHINGTON -- Five American troops were killed Monday during what the Pentagon is calling "a security operation in southern Afghanistan."
They died in what the Pentagon fears was fratricide.
The troops were part of a U.S./Afghan team conducting a joint patrol in the Arghandab district of Zabul province, in advance of Saturday's presidential runoff voting.
Pentagon Press Secretary Rear Admiral John Kirby said in a statement, "Investigators are looking into the likelihood that friendly fire was the cause. Our thoughts and prayers are with the families of these fallen."
Military authorities have yet to confirm it, but it's widely believed they were killed by weapons fired from an aircraft providing close air support. That aircraft was called in after the team was attacked by Taliban forces as they prepared to leave the area by helicopter.
Zabul province has long been a thorn in the side of U.S. and international military forces.
In 2009, concerned about the possibility of friendly fire incidents, the Department of Defense sent an urgent shipment of laptop computers and other electronic equipment to Zabul province and other locations in Afghanistan to prevent friendly fire.
The shipment was part of the FalconView mapping system developed for the U.S. Air Force to support Joint Terminal Attack Controllers (JTACs). Their job is to call in airstrikes.
In the heat of battle during the 13 years the U.S. military has been at war in Afghanistan, JTACs have called in many such airstrikes, some allegedly resulting in the deaths of U.S. troops.
In addition to air strikes, FalconView, was designed to help avoid incidents of friendly fire among ground forces, as was the case with Pat Tillman, NFL star turned Army Ranger, who was killed on April 22, 2004, while on patrol.
FalconView is a Windows-based, geo-spatial mapping software system created by the Georgia Tech Research Institute for the Department of Defense. It displays aeronautical charts, satellite images and elevation maps. It was targeted toward military mission planning users and oriented towards aviators and aviation support personnel.
It is believed that system is still being used by the U.S. military. The Air Force referred WTOP to U.S. Central Command (CENTCOM) for answers to questions about which system was being used at the time of the incident.
CENTCOM is investigating.
Monday's incident in Zabul is reflective of U.S. defense officials' concern about the persistence of the Taliban in the region and the evolving knowledge base of terror groups in Afghanistan.
The province, located in southeastern Afghanistan, next door to the Taliban stronghold of Kandahar, has been the scene of frequent violent attacks by the Taliban and other misfortunes for international military forces.
Including Monday's casualties; it's estimated, based on unofficial, open source information that 112 U.S. deaths have occurred in Zabul since November of 2001.
Only Helmand (452), Kandahar (368), Kunar (170), Paktika (134) and Wardak (115) provinces have more. There have been more than 2,100 U.S. casualties in all of Afghanistan during the war.
The last recorded casualties were on December 17, 2013, when a U.S. military helicopter crashed in Zabul killing six of those on board. The chopper came down after engine failure.
As U.S. combat troops prepare to exit Afghanistan later this year, U.S. government officials express hope that peace might be a dividend of America's longest war.
But Monday's attack in Zabul, has revived the concern that the Taliban, which once governed Afghanistan with ruthless impunity, is not ready to make peace with the idea of sharing power with an Afghan government backed by the U.S. military.
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