LOS ANGELES - G.I. Joe's second big-screen mission was just about to begin last year when Paramount suddenly called the troops back to base, delaying the release of "G.I. Joe: Retaliation" by nine months to convert it to 3-D. The move came just weeks after another movie based on a Hasbro toy, "Battleship," was torpedoed at the box office.

Fans will soon find out if it was worth the wait: "G.I. Joe: Retaliation" opens today.

Though director Jon M. Chu always wanted to make the film in 3-D, learning of the delay a month before the film was set to open was initially crushing.

"It's kind of like running a marathon and you're at the last leg and you're exhausted and you're right at the finish line ... and then someone trips you and says, 'Oh, that's not the line. That was just an illusion. It's actually double the time,'" he said in a recent interview. "Literally your body aches."

It's not unusual for movie debut dates to bounce around a bit before being buttoned down, as production schedules and competing releases are assessed. But lengthy, last-minute delays are rare. The studio had even begun some "G.I. Joe" advertising efforts when it announced the 3-D delay last May.

At the time, some speculated it wasn't just about adding dimension, but also adding more of rising-star Channing Tatum, who was featured in 2009's "G.I. Joe: Rise of Cobra" but didn't clock much screen time in the sequel.

Yet the filmmakers insist they didn't shoot any new footage for "G.I. Joe: Retaliation," saving the stars from shuffling their schedules for more than a couple weeks of promotional appearances. Instead, Chu and his team spent their time solely on converting the film to 3-D, and they hope fans will be so dazzled by the effects that they'll forgive the nine-month wait.

"We had to get in frame by frame and turn it into 3-D, which was a long, laborious task," Chu said, "but ultimately I think it really helps our movie."

But will it be enough to bring fans into theaters?

"Unfortunately, movies somehow get a stigma by moving (dates)," said producer Lorenzo di Bonaventura. "There's also some people who go, 'Oh, was that movie not good enough? Is that why you guys pushed it?' So you've got to work your way through some of that as well."

The producer had also hoped to make the film in 3-D originally, "but we didn't have time to do it properly," he said.

Chu had two 3-D movies to his credit ("Step Up 3D" and the 2011 documentary "Justin Bieber: Never Say Never"), and expected to approach the G.I. Joe sequel three-dimensionally, too. Even though it was shot in 2-D, the director said he brought a 3-D sensibility to filming.

"Depth is always part of my language now, only because I had to do it for the last four years. So every scene, even though it wasn't in 3-D, depth was a part of the frame," he said. "Of course, if I knew it was going to be 3-D, would I have done a couple things differently? For sure. But we wouldn't have done (the conversion) if we didn't look at the movie and think we have enough fun things in it to take advantage of 3-D."

Among the dimensionalized fun? Jets that soar past moviegoers' heads, and a high-flying fight among ninjas in the Himalayas.

Fans online seem excited about "Retaliation," which stars Dwayne Johnson and Bruce Willis, along with Tatum and others. The movie site Fandango.com reports positive Twitter buzz for the film, which is the only new action offering on a weekend when many students are on spring break.

Also opening are "Tyler Perry's Temptation," the romance-adventure "The Host" and the crime drama "The Place Beyond the Pines."

Waiting for a spring debut may pay off for G.I. Joe if the 3-D improves the film, said Dave Karger, chief correspondent for Fandango.

"The movie will have a harder time making summer money in late March," he said, "but it stands a better chance to be well-received now if it's a more of a crowd-pleasing film because of the 3-D."