Name that movie

[nadz0r]

It's bugging the hell out of me - what's the movie where there's a bunch of soldiers (US) and they're hooked up to this brain thing, which is simulating combat, and then they start having flashbacks and they're not sure what is real and what was part of this simulation? I think it ends somewhere near a beach and it's set in the desert. I'm sure the baddies were Middle Eastern.

Denzel Washington might have been in it, but I'm not entirely sure...