Then, the military ousted Prime Minister Thaksin Shinawatra, the brother of Thailand's recent leader. He currently lives in exile. The military remained in power for over a year.
In his announcement, Prayuth noted also that the coup was to "worship and protect the monarchy," alluding to the country's ailing 86-year-old King Bhumibol Adulyadej. Thailand is a constitutional monarchy.
This is Thailand's 12th successful coup since 1932, when the country's absolute monarchy dissolved. There have been seven other attempted coups.
In response to the military declaring martial law in Thailand earlier this week, the White House gave a cookie-cutter response fit for any country vaguely in this situation. Press secretary Jay Carney said the U.S. is monitoring the situation and is very concerned about the political crisis.
"The U.S. firmly believes that all parties must exercise restraint and work together to resolve differences through peaceful dialogue to find a way forward," Carney told reporters at Tuesday's daily briefing. "This development underscores the need for elections to determine the will of the Thai people."
At the heart of the political tensions are two groups. CNN explains:
Those are the so-called yellow shirts, predominately urban, middle-class supporters of the royalist establishment. They've been staging massive protests in the country's capital for months and boycotted elections in February.
Backing the government are the so-called red shirts, many of whom hail from the country's rural north and northeast.
This is the latest ouster in a series of political crises around the world, from Egypt to Ukraine.
Secretary of State John Kerry later on Thursday said he was "disappointed" with the decision by the military to stage a coup and suspend the constitution of Thailand, saying, "There is no justification" for it.
"I am concerned by reports that senior political leaders of Thailand's major parties have been detained and call for their release," Kerry said in a statement. "I am also concerned that media outlets have been shut down. I urge the restoration of civilian government immediately, a return to democracy, and respect for human rights and fundamental freedoms, such as press freedoms."
Additionally, Kerry called for new elections. While he noted the "long friendship" with the Thai people, Kerry said this will have "negative implications" for the relationship between the U.S. and Thailand, considering the U.S. law that restricts military assistance to countries that stage coups.