The military is using Buddhist monks under their control to push an ultra-nationalistic extremism into politics (as seen elsewhere in the world). They basically used it in the years prior to the coup to incite ethnic conflicts and justify military actions in certain regions including Rakhine where Rohingyas live. They cited that instability as the main excuse to stage the coup after election victory of Aung San Suu Kyi's party. This coup has been years in planning and execution when they realized they couldn't win the election fairly under the constitution they wrote because of the popularity of Suu Kyi's party.