Incredibly convincing cast and dialogue. In particular,
what the writers leave out -- but is obvious -- is how clueless
the soldiers and their families are, about what is happening
around them.
The attempt to almost-superstitiously maintain a home away from home lifestyle and relationships creates quietly effective,
building suspense in every episode.
What will happen if things go wrong is never beaten to death in
dialogue -- it either happens, and we see directly the impact, or
it remains a potential happening, and we are on the edge of our
seats.
The writers also use very cleverly what we, the audience know as a
powerful contrast with what the characters do not know or cannot
even imagine. Terrific sustained suspense titched from scenes of
everyday life in a that place and time.