Ben Stiller is defending his decision to erase images of the World Trade Center towers from his comedy Zoolander, saying he did what he thought was appropriate at the time.

Stiller plays a clueless male supermodel in the movie, which he also directed and co-wrote. In a couple of scenes, the Manhattan skyline is visible in the background, but the twin towers are gone.

He fired back at producer Michael Mailer, who was quoted in an Oct. 24 New York Times article about the skyline as saying it was "execrable" to alter the scenes.

Zoolander opened nationwide on Sept. 28, barely two weeks after the Sept. 11 terrorist attacks that destroyed the World Trade Center.

"The appropriateness of releasing a comedy at all at that time was under serious discussion," Stiller wrote in a Times letter to the editor, which ran Monday. "In deciding to go ahead, I had to make an immediate judgment about the skyline shots, which were indispensible to the story. I decided to edit out one shot, and to obscure the towers in another.

"I felt that people who chose to see the movie as escapist entertainment were not looking for another reminder of tragedy."