Contacted by KREM-TV in Spokane, officials at Naval Air Station Whidbey Island admitted that one of its aircraft was responsible.
Photos sent to KREM 2 by multiple sources showed what appeared to be a drawing of male genitalia on Thursday.
"The Navy apologizes for this irresponsible and immature act", she added.
Social media was filled with reports discussing the incident and photographs showing the phallic sky images.
The Navy also told Fox News the crew has been grounded and that a "thorough investigation" is being conducted.More news: Gwen Stefani Praises 'The Voice' Coach Blake Shelton After Sexiest Man Backlash
"After it made the circles at the bottom, I knew what it was and started laughing", said local resident Ramone Duran.
A mother who lives in Okanogan who took pictures of the drawings reached out to KREM 2 to complain about the images. "I thought it was pretty amusing, and so did he", says Misty Waugh, whose 12-year-old son texted her a photo of it.
The Federal Aviation Administration, a government agency that regulates USA airspace, said the drawings did not appear to pose a safety risk and it "cannot police morality".
A spokesperson for the FAA told the station that unless a pilot's actions pose a safety risk there's nothing it can do, adding that the agency "cannot police morality".