Passage: Following the release of Terminator 3 in 2003, producers Andrew G. Vajna and Mario Kassar contracted Nick Stahl and Claire Danes to return as John Connor and Kate Brewster in another film. Director Jonathan Mostow helped develop the script, written by John Brancato and Michael Ferris, and was set to begin production in 2005 after completing another film. It was known by then that Arnold Schwarzenegger's role would be limited, as he had assumed office as Governor of California. The producers sought to have Warner Bros. finance the picture as they did for Terminator 3. In 2005, Stahl said John and Kate would be recast as the story jumped forward in time. By 2006, Metro-Goldwyn-Mayer (a successor to Orion Pictures and current owners of the Hemdale Film Corporation library, distributor and producer of the original film, respectively) was set to distribute the fourth film as part of the new CEO Harry Sloan's scheme to make the studio a viable Hollywood player.On May 9, 2007, it was announced that production rights to the Terminator series had passed from the feuding Vajna and Kassar to the Halcyon Company. The producers hoped to start a new trilogy. The purchase was financed with a loan by Pacificor, a hedge fund from Santa Monica. By July 19, the project was in legal limbo due to a lawsuit between MGM and Halcyon subsidiary T Asset. MGM had an exclusive window of 30 days to negotiate for distribution of the Terminator films. When negotiating for Terminator 4, Halcyon rejected their initial proposal, and MGM suspended negotiations. After the 30 days were over, MGM claimed that the period during which negotiations were suspended did not count and their exclusive period was still open. Halcyon asked a court for an injunction allowing them to approach other distributors. Later, the lawsuit was settled and MGM got a 30-day right of first refusal to finance and distribute the fifth Terminator film.Finally, Warner Bros. paid $60 million to acquire the United States distribution rights of Terminator Salvation; Sony...

Question: Who suspended the negotiations?
MGM