I don’t know. Maybe read article. It says „Korean military”. According to them stock Android with 3rd party security app is acceptable and has no security concerns. Article itself highlights that 3rd party security apps are inferior and security holes in Android OS are basically neglected by Korean military since they will be addressed in updates at some point.

OS does not matter when approach to security so superficial. Judging by this article Korean military has less robust security practices than some banks.

Everyone here talking about some hypothetical Android based custom OS built for Korean military which does not exist and it is not what Korean military doing. They are allowing stock Android OS with „security app”. Not surprised they are not building custom OS because it is economically idiotic idea. You need army of cyber security experts familiar with Android OS architecture that will review whole OS code and customize for military. Then you need to pen-test it and keep on doing it on each upstream OS update or fork it and maintain internally. Which is another can of worms coz you’ll need to make sure internal fork works fine with up-to-date versions of apps. Otherwise you just have dumb smartphone with higher risk of vulnerabilities in outdated apps. At this point as I said, just force sensitive staff to use dumb phone or internal landline.

And don’t tell me “but Samsung is Korean they can do it for Korean military”. It doesn’t not change the fact that it will cost astronomical amount of money and time. Can Samsung do it? Probably yes. Will Korean military be able to offer enough money to probably the only local company that can do it which also has revenue of approx. 20% of Korea’s GDP. I doubt.