Refers to the governing or commanding body of a military force, often used in news or formal contexts.
The military authorities have launched an investigation into the incident.
The information was released by the military authorities.
軍政 means military government or administration, focusing on governance by the military, whereas 軍当局 is a more general term for the military command or authorities.
Compound of 軍 (gun, 'military') and 当局 (tōkyoku, 'authorities'). The term is a straightforward Sino-Japanese construction.