EXCLUSIVE: The sequel G.I. Joe: Retaliation was supposed to come out this summer on June 29th. But I’ve learned that Paramount is moving the movie nine months to March 29, 2013, to add 3D. “We’re going to do a conscientious 3D job because we’ve seen how it can better box office internationally,” one of the studio execs just told me. “Jim Cameron did all of Titanic‘s 3D in post — and look how well that movie turned out.” Hollywood is shocked that Paramount vacated the primo date, especially because Paramount blew a wad on a Super Bowl commercial and already was starting TV and outdoor ads for GI Joe 2. Paramount has had luck delaying films before: its decision to move Martin Scorsese’s Shutter Island gave the director his biggest box office hit ever. And right now, 3D is huge internationally, with Russia and China building new 3D theaters by the week. Also the execs say that the blockbuster performance of The Hunger Games shows that March can be a prime time of the year to release movies. Of course, Paramount had to talk its partners on GI Joe 2 into the extra nine months of carrying costs — MGM, which has 25%, and David Ellison’s Skydance, which has another 25%. The $125M-budgeted actioner stars Channing Tatum, Dwayne ‘The Rock’ Johnson, and Bruce Willis and is directed by Jon Chu.