Mobile is one of the ICBMs (IoT, Cloud, Big-Data, Mobile) of the Fourth Industrial Revolution, and one of the technologies that will drive the future. In recent years, there has been a significant amount of research on how the military can utilize mobile technology for various needs in national defense, and some have proactively introduced and are using it. The Army has been studying the introduction of the Army Mobile Office System (AMOS) since 2019. The Army's AMOS system, which is being developed to date, has achieved a lot, but there is still room for improvement. In this paper, we will discuss the various mobile systems that have been introduced or are in the process of being introduced in the Army, especially the AMOS system, which is still expanding its concept and is expected to be very useful, and suggest ways to further secure the aforementioned security and the direction that the Army AMOS system should go in the face of the need for telework.