Just seen this thread. Apparently this location is used frequently for their operations. I wasn't present, but a few friends were out riding last year and came upon the same operation at the same location. They also stopped, took pics then the helo took off. They didn't notice troops on the ground but maybe the operations were complete and the troops were already back on the helo. My friends proceeded down the road after the help took off.
I've also witnessed helo operations in the vicinity of the "50 fields" area in Greenwood.