This is as slender as many of the hunches on this site, yet the first film I thought of was NO WAY OUT: it's 80s, there are lots of scenes in offices (if not office "buildings"), there is a female (Sean Young) who seduces a military man AND a high-ranking businessman (really a politician) - Kevin Costner and Gene Hackman, respectively - there's lots of suspicion that she is a Soviet agent though (iirc) there's a twist at the end that one of the other characters was actually a spy (maybe instead of Young). It's been 30+ years since I watched it. And, for what it's worth, Wikipedia claims it was based on a book that was turned into two previous movies from the 50s - maybe you're even thinking of one of those:
https://en.wikipedia.org/wiki/No_Way_Out_(1987_film)