The king's role
King Bhumibol Adulyadej has headed Thailand's constitutional monarchy for over 60 years, but the 86-year-old's health is failing. While he is revered across the country and seen a source of stability, there are concerns about the future.
"The 500-pound gorilla in the room is the health of the king, how long he'll be around and who will follow," Steve Vickers, CEO of Steve Vickers & Associates, a risk mitigation consultancy, told CNBC.
Army chief Prayuth Chan-ocha was expected to meet the king on Friday to explain the army's move.
The coup has been condemned by a number of countries including the U.S., the European Union and Thailand's neighbors in Asia -- Japan and Australia.
Countries such as the U.K. and Singapore meanwhile have issued travel warnings to citizens traveling to or in Thailand.
Kristie Kenney, U.S. ambassador to Thailand, told CNBC: "The safety of U.S. citizens is my top priority and the top priority of our embassy."
"We have advised U.S. citizens of the coup, of the curfew which is 10pm to 5am throughout Thailand and we have asked them to use caution," she added.