The only information there resembling 'formal permission' is this quote - >On June 10, 2012, Lakota elders ritually blessed two new South Dakota Army National

The only information there resembling 'formal permission' is this quote - >On June 10, 2012, Lakota elders ritually blessed two new South Dakota Army National Guard UH-72A Lakotas at a traditional ceremony on the Standing Rock Reservation in North Dakota. Ceremonies like these happened often over the past several decades.