Exact dates and locations of her shows in the gulf region were not made public by the USO.
"There are no details and no dates for safety and security reasons," publicist Jessie Schmidt of Nashville, Tenn., said Monday.
"They never release exactly where the tours are happening, or exactly when they're happening. All I can share is that it is sometime before too long from now. But I don't even know the exact locations that she's going in the Persian Gulf," Schmidt said.
Schmidt said USO officials approached Underwood, originally of Checotah, Okla., about touring the Persian Gulf region several months ago and plans have been in place "for quite some time."
"She is completely excited about it," Schmidt said. "She does have some band members that are able to go with her over there, so they're just all really jazzed.
"When she does return from the tour we can say that she's just come back, and hopefully we'll have some photos that they'll service to the press from over there as well," Schmidt said.
Underwood also was seen Monday on a segment of the Oprah Winfrey Show taped last week, performing her hit song, "Jesus Take the Wheel," and joining fellow guests Tony Bennett, Josh Groban and Michael Buble for a rendition of Stevie Wonder's "For Once in My Life."