Additional fun fact about Ronin, John Frankenheimer recorded and cut two alternative endings. Test audiences didn't like the two endings even though he did, and had to follow what the audience wanted due to the production studio's wishes. He preferred the ending where she got kidnapped though, he thought it was a better wrap for the movie.
SPOILERS BELOW - IF YOU HAVEN'T SEEN THE MOVIE DON'T READ OR WATCH(but if you haven't seen this master piece in filmmaking, do yourself a favor and go watch it ASAP!)
The ending as the movie shipped consisted of Sam and Vincent in the cafe, CIA asset comes and picks up Sam, and Vincent leaves shortly after - credits.
The two other endings had Dierdre in it. In both, she is outside the cafe in Paris. First one she leaves by going to her car, and drives off - then Sam and Vincent leave. Second one she leaves and as she is getting into the car, she gets kidnapped by IRA members in a black van. Videos I could find are as follows:
Original Ronin Ending:
Alternative Ending #1(Dierdre with IRA):
Can't find the other, but it's similar to to alternative ending on YouTube except she drives away instead of getting kidnapped by the IRA.