Williams, who died Monday of an apparent suicide at age 63, went on his first tour that year to perform for troops in Afghanistan and Turkey, according to the USO.
His passport would eventually include stamps from doing shows in Bahrain, Djibouti, Germany, Iraq, Italy, Kuwait, Kyrgyzstan, Qatar, Spain and the United Arab Emirates, the Military Times reported. There were visits in the United States as well.
One particularly noteworthy moment on the USO stage happened at Camp Arifjan, Kuwait, in December 2007, the year after Williams got out of rehab. He was joking about rehab being a good thing -- "Because I was violating my standards faster than I could lower them" -- when all of a sudden the entire audience turned its back on him as a horn played.
"I'm not gonna forget that. I've never had an entire audience just go 'forget you'" he said, turning his back momentarily to the crowd. "I was also wondering what's coming from that way. When an entire group of military people turns that ... way."
Then he asked if someone could tell him what had just happened. Turns out it was "retreat," the end-of-day ceremony that requires troops to turn toward the flag as it's lowered.
Williams quickly had the audience laughing again as he riffed off the notion of retreat in an operational sense, then compared his experience to having a partner suddenly turn away without explanation in the middle of sex.
The "Mork & Mindy" star told Parade in 2013, "I do those [shows] because it's like the real version of 'Good Morning, Vietnam,' meeting people and seeing what I can do to help. They’re the best audiences I've ever had. The most powerful experience is visiting the wounded in ."
In another interview, he said did it because he got so much more out of the effort than he put into it.
Gary Sinise, another actor who publicly supports the
"R.i.P Robin Williams," Sinise wrote. "His genius as artist & comedian will B missed & his support of R troops no doubt was much appreciated by all who serve."
The real-life Cronauer, meanwhile, told WTOP-FM on Tuesday that he and Williams didn't meet until the "Good Morning, Vietnam" premiere.
"Barry Levinson, the director, wouldn't let me anywhere near [Williams] or even the set because he was worried if [Williams] and I met, he would start to do, subconsciously, an imitation of me, which, of course, would change the characterization," the Virginia lawyer said.
Cronauer, who swapped Christmas cards with his big-screen alter-ego over the years and told the radio station that he planned to re-watch "Good Morning, Vietnam" this week, noted that he has always been a much more laid-back guy than the memorable character the comic created for the film.
"That was all Robin Williams," he said. "All Robin Williams."