Democrats have spent weeks attacking Schultz and openly worrying that an independent run would split their base and hand the White House back to President Trump.
Two Democratic candidates are veterans: Rep. Tulsi Gabbard of Hawaii and South Bend, Indiana, Mayor Pete Buttigieg.
Gabbard served in Iraq with the Hawaii Army National Guard from 2004 to 2005, and Buttigieg is a veteran of the Afghanistan War, having served a tour with the Navy Reserve as an intelligence officer.
Soon after Schultz's comments aired, Buttigieg tweeted he didn't "recall seeing any Starbucks" in Afghanistan, where he deployed in 2013.
"I apologize to @PeteButtigieg and @TulsiGabbard who served our country honorably,” Schultz wrote on Twitter.