https://www.foxnews.com/world/why-is-the-military-taking-control-in-burma
https://www.foxnews.com/politics/us-expresses-grave-concern-over-reports-of-military-coup-in-burma-will-take-action
I wish I knew more about Burma. It is a mystery to me.
I suspect this coup is more a confirmation of the de facto reality in Burma for the last few decades.
Aung San kuu kyi was in reality always the public face of the government and so long as she fell in line as their puppet would remain. It seems that she was not sufficiently politically reliable for them any more.
https://www.foxnews.com/world/burma-military-crackdown-on-anti-coup-protests-leaves-at-least-2-dead
Burma (Myanmar) has been a military dictatorships for many, many decades. Every once in a while the military tries "sharing" power with a civilian government to appease international sensibilities, but it never turns out well. In the 1950s Burma and Britain successfully fought off a Communist insurgency and the military has been entrenched since then. Their success against the commies was one of the primary reasons the USA thought it could win in Vietnam, but we did a poor job of following their model in a situation that had a few different parameters.
Protests are still going on.
https://www.foxnews.com/world/burma-protesters-take-to-streets-to-decry-coup-as-military-uses-teargas