(CNN) - Amazon has turned off the preorder function for DVD's of prominent Warner Brothers Films, as it seeks to raise pressure on the company during negotiations.
The missing preorder button illustrates the aggressive stance Amazon is taking in its negotiations with suppliers.
Other retailers play hardball too, but Amazon's gamesmanship is especially visible because it's online.
For the past month Amazon has been in a public dispute with Hachette, a major publisher, over terms for e-book sales.
An Amazon spokesperson did not respond to a request for comment on the Warner Brothers situation.
And a spokesman for Warner Brothers declined to comment.
Warner Brothers is owned by Time Warner, the parent company of CNN.
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