Judging from the spacing, location and placement of these structures along the perimeter of the facility, I'd say they are more likely guard tower/sentry positions of some kind. If you look at the apparent height of each (based off of the shadow length) and compare it to that of the buildings...they appear to be about the same height. Sitting out there like that, they would make awfully easy targets for attacking aircraft or UAVs otherwise.

IKEIK