South Korean President Yoon Suk-yeol on Tuesday declared martial law in an unannounced late-night address broadcast live on YTN television, reports "Reuters".
Yun said he had no choice but to resort to such a measure to protect free and constitutional order, saying opposition parties had taken the parliamentary process hostage to plunge the country into crisis.
"I declare martial law to protect the free Republic of Korea from the threat of North Korean communist forces, to root out the despicable pro-North Korean anti-state forces that are robbing our people of freedom and happiness, and to protect the free constitutional order", Yoon said.
In the address, he did not say what specific measures would be taken.
Yun cited a motion by the country's opposition Democratic Party, which has a majority in parliament, this week to impeach some of the country's top prosecutors and its rejection of the government's budget proposal.