I just finished "Rendezvous", a short story by Nelson DeMille.
(I listened to the audio version.)
"Rendezvous" is a long short story about a U.S. Army patrol in Vietnam that is "hunted" by a Vietcong sniper.
The hook? The sniper is a young female, but she's as deadly and cold-hearted as any male enemy could be.
DeMille, as some readers will know, saw combat as a U.S. Army officer in Vietnam. Therefore, the authenticity is there, as is the tension.
Because this is a short story, "Rendezvous" isn't filled with exceptionally memorable characters. However, the ending is quite haunting.
If you like this one, I would recommend DeMille's (rather lengthy) novel about Vietnam, Up Country.