The Royal Thai Army has taken control of the country in a non-violent coup and suspended the constitution, as it looks to resolve the long-running political crisis.
The military, which invoked martial law on 20 May, also announced a night-time curfew across the country, and ordered several cabinet ministers, including the ousted Prime Minister Yingluck Shinawatra, to immediately report to the new governing military commission.
Thai Army chief general Prayuth Chan-Ocha said the takeover was needed to reform political, economic and social structures.
"We ask the public not to panic and to carry on their lives normally," Chan-Ocha said.
A statement played on national television said: "In order to run the country smoothly, [coup leaders have] suspended the constitution of 2007, except for the chapter on the monarchy."
The move, which has banned political gatherings and suspended TV broadcasting, comes after the second round of talks between the military and political leaders on how to resolve the political turmoil broke down.
Since November 2013, Thailand has witnessed several demonstrations aimed at ousting the government. At least 28 people have died in protests, with hundreds injured.
Last month, Yingluck Shinawatra and nine cabinet ministers were ousted from office on charges of nepotism and power abuse.
Meanwhile, the military takeover, which represents the 12th coup since the 1932 revolution, has attracted sharp condemnation from the international community, including Germany, France, Japan, Singapore, as well as the UK and US.
US Secretary of State John Kerry said the coup will have negative implications on the US-Thai relationship
"We are reviewing our military and other assistance and engagements, consistent with US law," Kerry said.