What does "stop-loss " mean ?

Question

it's the name of a movie about Iraq-U.s war in which a soldier is called stop-lossed when he returns to Iraq.

Answer 1

Soldiers join the service for a certain amount of time. After that, they're normally allowed to leave. But if there's a stop-loss in effect, they can't leave when their time is up, but have to stay for a certain amount of time extra.

It's called stop-loss because it's meant to stop the branch from losing their soldiers - to keep the numbers up enough that they can function properly.