South Korean President Yoon Suk Yeol on Tuesday (December 3) declared martial law in an unannounced late night address broadcast live on YTN television, claiming he would eradicate "shameless pro-North Korean anti-state forces."

He did not cite any specific threat from the nuclear-armed North, however, instead focusing on his domestic political opponents.

Yoon said he had no choice but to resort to such a measure in order to safeguard free and constitutional order, saying opposition parties have taken hostage of the parliamentary process to throw the country into a crisis.

The surprise move sent shockwaves through the country, which had a series of authoritarian leaders early in its history but has been considered democratic since the 1980s. The Korean won was down sharply against the U.S. dollar.