It is unlikely any of them are enlisted military. No visual displays of a tattoo on any of them. It is not likely they are run of the mill millinials. I would expect at least a few would have man buns, some tats, and some facial hair.
They were probably attending a local mil/fed school at pentagon/dia/quantico etc. and had the saturday off to play around. All of the guys are in great shape. Any real op would have been the opposite of this. Facial hair, comms, spacing. This group of guys didn’t care. Nobody would do this working. My guess navy, except the guy in middle. He’s army as can be.
How about officers? Looks like a group of Second Lieutenants or Ensigns.
Don’t know if they still do, but the Secret Service used to recruit heavily from Mormons because of their religion’s clean-living rules. No alcohol, tobacco, or even caffeine, etc.