Mattis said he believed that the US should stay in the deal at a Congressional hearing. Are you implying that he told them something that he believed was false?
Starts at the 40sec mark.
[video=youtube;-oU1becPOys]https://www.youtube.com/watch?v=-oU1becPOys[/video]
What I'm saying is, at their level we really don't know and neither does the media. You can speculate, but the stakes are too high in the game they play to put all the cards on the table.