These are desert night camo pants that were used in the US Military. The camo was made to disrupt Soviet era night vision equipment, however it was quickly proven to be ineffective. These trousers run a little large. You can wear them over the standard BDU uniform as an additional layer during cold desert nights. The trousers have pocket flaps for accessing waist and cargo pockets, as well as full back pockets.
This is an awesome post Cold War camo that is getting harder to find!