Based on Suming's experience, there's a very simple method to differentiate the identity of an armed group, whether it's government-affiliated or a private military.
If it's a legitimate government force, they usually announce themselves and shout orders, even when apprehending criminals, having the absolute advantage, and implementing an encirclement. This is because any government force acts on the 'righteous path', backed by the law, at least ostensibly.
Unless the other party has hostages or is the type of ruthless terrorist who can be shot on sight.
On the contrary, illegal private militias tend not to reveal their identities, simply put, they dare not escalate the situation.
The group descending from the helicopter hovering above, aside from an initial shout to drop weapons, didn't utter another word, silently descending, and was soon to approach the stone bridge below.