Just watched it again. Butler uses a couple OTF knives, probably the Micro-Techs others have stated, but when he stands in his Treasury Dept. office he is wearing a horizontal small of the back (Scout) carry fixed blade. This knife is the one he uses in the interrogation scene with the 2 Korean terrorists. I finally got a really good look at it. It is a Gerber CFB fixed or Yari II. It's their modified drop point tanto with a partially serrated blade, 1/8th inch thick, approx. 4.25-4.5 inches long. The CFB uses 154CM while the Yari uses S30V steel. Otherwise the two knives are pretty much identical. Only weighs about 4.5 ounces or so.
I liked the movie and the way it focused on the action and tactical use of the weapons instead of going for posing scenes to highlight the "Cool Factor" of the terminal toys.