Haven't read it. Is there something about that era (Vietnam era) that is important to the story somehow?
I am a big fan of Clancy’s Jack Ryan series, up to and including Rainbow Six. After that his books got increasingly worse and worse. WR is set during the Vietnam war, and is an origin story about John Clark, a recurring character in the Jack Ryan books. The whole setting is important to the story, both geographically and politically. I can already tell this movie will be utter drivel.
The WR story done properly would have made an awesome movie, or maybe even a miniseries.