South Korean President Yoon Suk Yeol declared martial law on Tuesday in an unexpected late-night television address, announcing plans to "eradicate shameless pro-North Korean anti-state forces" in a move that sent shockwaves through the country's financial markets and political establishment, according to Reuters.
Speaking in a live broadcast on YTN television at 11 p.m. local time, Yoon announced the first martial law declaration since 1980 in what appeared to be primarily aimed at his domestic political opponents rather than any specific threat from North Korea.

The Yonhap news agency reported that the military would ban activities by parliament and political parties, while placing media outlets and publishers under martial law command control. The entrance to the parliament building has been blocked, according to the agency.
"I declare martial law to protect the free Republic of Korea from the threat of North Korean communist forces, to eradicate the despicable pro-North Korean anti-state forces that are plundering the freedom and happiness of our people, and to protect the free constitutional order," Yoon said in his address.
South Korean media later reported that the South Korean military has withdrawn from the parliamentary building, and the president has announced the dismissal of military rule.

The dramatic move rattled markets, with the Korean won falling sharply against the US dollar, prompting a central bank official to tell Reuters they were preparing stabilization measures if needed.
Lee Jae-myung, leader of the opposition Democratic Party which holds a parliamentary majority, urged citizens to gather at the National Assembly. "Tanks, armored personnel carriers, and soldiers with guns and knives will rule the country," Lee warned in an online livestream. "The economy of the Republic of Korea will collapse irretrievably."

The White House has not immediately responded to requests for comment. Approximately 28,500 US troops are stationed in South Korea, but a spokesman for the US military command did not answer repeated phone calls, Reuters reported.
Yoon cited recent actions by the Democratic Party, including a motion to impeach top prosecutors and the rejection of his government's budget proposal, as evidence that opposition parties had "taken hostage of the parliamentary process." On Monday, his ministers protested the opposition's move to cut more than 4 trillion won from the government's budget proposal.

South Korea, which emerged from a series of authoritarian leaders to become a democracy in the 1980s, now faces its most serious constitutional crisis in decades as the nation awaits specific details of the martial law measures to be implemented.