(CNN) - The four Americans killed in a suicide blast Wednesday in northern Syria possessed unique expertise for conducting highly classified intelligence-gathering missions in combat zones, according to several defense officials who have spoken to CNN.
The US military has not yet publicly acknowledged why the team had traveled to a busy commercial area in the city of Manbij, which also housed a restaurant that many US government personnel frequented in the past.
In fact, within hours of the attack, the first statement from the US military said the team had been "conducting a routine patrol." But that was followed with another statement that four Americans had been killed "conducting a local engagement," and three additional US troops had been injured.
Several officials told CNN the Pentagon is still assembling details of the mission, and what exactly took the team to that location at that time. But if the military's broad description of the event as a "local engagement" is accurate, it indicates the team was potentially meeting with a sensitive source to gather intelligence or may have even been using electronic equipment to conduct eavesdropping and electronic intercept missions.
As with all attacks, the military is investigating what happened, and how it happened, officials say. Regardless of the exact mission and the reason the group had left the security of the base, there would have been detailed planning and an assessment of the risk at the time they planned to travel.
Military investigators may look at whether US personnel had traveled to the spot too often in the past, and their patterns of activity inadvertently became predictable to adversaries who might be conducting surveillance on them.
At times, US personnel also make the decision to visit local areas for other reasons, such as to buy supplies and interact with local shopkeepers.
But officials also strongly emphasize that these types of military intelligence experts often take on the most dangerous jobs, traveling to risky areas to do the job of meeting with sources and gathering intelligence. In these unique circumstances, decisions can be made to travel in civilian vehicles and not wear body armor so the team can more readily blend into the local area.
Navy Chief Cryptologic Technician (Interpretive) Shannon M. Kent was from upstate New York. She was a sailor assigned to Cryptologic Warfare Activity 66, based at Fort George G. Meade, Maryland, according to public statements from the Navy.
But a defense official with direct knowledge of that specialty says her unit was "sensitive." She would have had the specific skills for planning and conducting eavesdropping and translating the electronic messages that would be gathered on such a mission, the official said.
The Navy's own public website defines the job of cryptologic technicians this way: "Sailors in the Navy Cryptology community analyze encrypted electronic communications, jam enemy radar signals, decipher information in foreign languages and maintain state-of-the-art equipment and networks used to generate top-secret intel."
"She was a rock star, an outstanding chief petty officer, and leader to many in the Navy Information Warfare Community," said Cmdr. Joseph Harrison, commanding officer of her unit.
Also killed on the mission was Scott Wirtz, a Defense Intelligence Agency civilian and former Navy SEAL.
The agency said Wirtz was an "operations support specialist," which meant his expertise was to "manage, guide, and oversee human intelligence collection operations enabling DOD to meet national security information requirements." Wirtz had completed multiple deployments for the agency in the Middle East after leaving the Navy.
Army Chief Warrant Officer 2 Jonathan Farmer was also killed in the blast. He was assigned to 5th Special Forces Group (Airborne) at Fort Campbell, Kentucky. One military official said Farmer's assignment would have involved him collecting intelligence in his immediate area of operations.
The fourth person killed was identified as Ghadir Taher from East Point, Georgia. According to her brother Ali Taher, she worked as an interpreter for the Army through a company called Valiant. She was a naturalized US citizen and immigrated from Syria in 2001.
Manbij was freed of ISIS control in 2016. While the US suspects an ISIS sleeper cell was responsible for the latest attack, according to one official, it is not clear how prevalent ISIS remains in the immediate area and what operation would have required a team with such highly technical and intelligence expertise.
It's not the first attack against sensitive US units in the Manbij area.
In March 2018, two soldiers, one American and one British, were killed in an improvised explosive device blast. They were on a classified mission to "kill or capture a known ISIS member," according to a Pentagon official at the time.
The US military released few details about that mission, which killed Master Sgt. Jonathan J. Dunbar. One indicator of the sensitivity of the mission is Dunbar was identified publicly by the Army only as being "assigned to Headquarters, U.S. Army Special Operations Command, Fort Bragg, N.C."
That specific language has been used in the past when troops killed in action have actually been part of the Army's elite Delta Force, a counterterrorism unit that is not publicly identified.
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