Editor's note: This article was originally published at 10:36 a.m. EDT on May 3 and has been updated. Some details have been withheld at the request of the Defense Department.
Defense Secretary Ash Carter said "it is a combat death" at a Tuesday press conference.
Special operations forces have been embedded with anti-Islamic State group fighters for nearly two years, training and assisting the resistance to the group that overran northern Iraq in early 2014.
In December, the Pentagon announced it was sending more special operators to Iraq to conduct raids. Experts say the raids have taken a devastating toll on ISIS leadership.
Contrary to reports by other publications, he did not attend the Naval Academy, academy spokesman Cmdr. John Schofield confirmed on Wednesday.
Keating enlisted in 2007 and reported to his first SEAL unit in June 2008, according to Navy personnel records. He served with three units in all, earning the Bronze Star with combat "V," three Navy and Marine Corps Achievement Medals, an Army Achievement Medal and two Combat Action Ribbons.
His deployment medals include a NATO Medal and campaign medals for Iraq and Afghanistan.
A 2004 graduate of Phoenix's Arcadia High School, Keating was city and region champion in the 1,600-meter run as a sophomore, junior and senior.
Rob Reniewicki, Keating's former track coach at Arcadia, said he has kept it touch with him through Facebook over the years, and he is heartbroken by the news.
"I'm devastated. I'm crushed. I'm trying to hold myself together," Reniewicki told Phoenix TV station KTVK.
Keating was planning to get married in November, Reniewicki said.
Keating earned all-city and first-team all-state honors as a senior, according to Indiana University, where he ran in college.
Arizona Gov. Doug Ducey ordered all state flags be lowered to half-staff from sunrise to sunset Wednesday in honor of Keating.
Keating's grandfather, Charles H. Keating Jr., who died in 2014 at age 90, was the notorious financier who served prison time for his role in the costliest savings and loan failure of the 1980s.
The Associated Press contributed to this report.