Numerous videos on social media showed an unarmed Lakota medevac helicopter hovering over demonstrators. Its Red Cross markings, visible on the aircraft’s belly and side, was flown by the Washington D.C. Army National Guard. Another helicopter snapped tree limbs and sent people scurrying from the deafening roar, the New York Times reported.

The use of a helicopter with Red Cross markings was an abuse of global norms that could help erode its neutral symbolism, military justice experts said.

“This was a foolish move,” said Geoffrey Corn, a former Army lawyer and professor at the South Texas College of Law in Houston. “The symbolic significance of the Red Cross is pervasive: It denotes a ‘noncombatant’ function of the armed forces.”…

The use of a helicopter’s rotor wash, the downward rush of air from its rotors, is a common military tactic to incite fear, disperse crowds and warn of other capabilities, like rockets and guns, said Kyleanne Hunter, a former Marine Corps pilot who flew Cobra attack helicopters in Iraq and Afghanistan.