Chief Petty Officer Jason C. "JJ" Finan, 34, had been attached to a Coronado, California-based SEAL team at the time of his death, according to a source with close knowledge of the events. Military.com is not releasing the name of the team to avoid compromising operational security.
Finan was killed when his Humvee rolled over an improvised explosive device as it was exiting a minefield, the source said. No other teammates were injured.
In an interview with Stars and Stripes in Irbil, Iraq, this weekend, the commander of the coalition fight against the Islamic State, Army Lt. Gen. Stephen Townsend, provided more context, saying Finan had spotted one IED and was directing teammates and civilians to safety when his vehicle struck another roadside bomb.
A Defense Department official confirmed to Military.com that Finan, as a member of Explosive Ordnance Disposal Mobile Unit Three, had been attached to a special operations task force serving in Iraq.
SEAL teams frequently have outside augments serving in specialized capacities, such as explosive ordnance disposal.
In a pair of emails to unit family members, the commander of the SEAL team paid tribute to Finan and the sacrifice he made for his brothers-in-arms.
"JJ was the definition of a professional and a loyal teammate and he will be deeply missed," the commanding officer wrote. "He answered the nation's call and paid the ultimate sacrifice for freedom, and for it we will be forever grateful."
The officer said the team planned to honor Finan formally and informally in coming weeks in a variety of ways.
"Meanwhile, we will remain resolute," he said. "Our SEALs and sailors currently deployed will continue to do our nation's work with the utmost dedication and professionalism ... this country is blessed to have such patriots as JJ."
Finan is the first U.S. service member to be killed supporting the Iraqi Security Forces' assault on Mosul, the last major stronghold for the Islamic State in Iraq.
A 13-year sailor, Finan was a master explosive ordnance disposal technician who had previously deployed to Iraq and Afghanistan and had also served aboard the aircraft carrier Ronald Reagan early in his career.
He had twice been awarded the Combat Action Ribbon and had a number of awards honoring exemplary service, including the Navy and Marine Corps Commendation Medal with Combat Valor Device.
In just one day, a GoFundMe page created to support Finan's family has raised more than $21,000.