Series 3 location

Somewhat hope it will be somewhere quite contentious such as Syria or Ukraine.
They did mention deploying to Syria towards the end of Series 2 so a big maybe?

Honestly, although it would be somewhat controversial if it was a realistic theme it could pull of a Saving Private Ryan level of detail and accuracy(probably wouldn't, but it is something to work for). But at the same time try to keep it balanced.

Ukraine would also work, it may also be a bit less controversial. It does also have the bonus of being a massive change in environment, going from desert to more temperate and colder environment. It would make a good change and keep the series original.