South Korean prosecutors said on Thursday that they have opened an official investigation in President Yoon Suk Yeol’s attempt to put the country under martial law. Interior Minister Lee Sang-min and former Defense Minister Kim Yong-hyun are also part of the probe.

Police said the president was under investigation for "insurrection" and Kim, who had already resigned following the incident, has been placed under a travel ban and forbidden from leaving South Korea.

The country's opposition Democratic Party on  Wednesday introduced a bill to impeach President Yoon Suk Yeol over his brief declaration of martial law, while ministers began tendering resignations.

"The Yoon regime's declaration of emergency martial law caused great confusion and fear among our people," Democratic Party member Kim Seung-won told the National Assembly as the impeachment motion was tabled.

"The people and the aides who protected parliament protected us with their bodies. The people won, and it's now time for us to protect the people," he continued.

"We need to immediately suspend the authority of President Yoon. He has committed an indelible, historic crime against the people, whose anxiety needs to be soothed so that they can return to their daily lives."

According to the South Korean Yonhap news agency, the opposition is seeking a vote by Saturday.

By law, the motion will be scrapped if it isn't voted on within 72 hours of its parliamentary introduction.

Yoon's party to oppose impeachment bill

Yoon's ruling People Power Party (PPP) has stated its intention to oppose the motion, but the opposition needs only eight defections for the bill to pass.

18 PPP lawmakers already voted to rescind Yoon's martial law order in an emergency sitting in the early hours of Wednesday morning, and party leader Han Dong-hun has called the President's actions "unconstitutional."

Nevertheless, he said his party would still vote against impeachment to prevent "prevent damage to citizens and supporters caused by unprepared chaos."

If Yoon were to be impeached and suspended from exercising power, Prime Minister Han Duck-soo would fill in as leader, according to South Korea's constitution.

Were he to resign or be otherwise removed from office, new elections would be held within 60 days.

Ministerial resignations

In the meantime, Yoon on Thursday accepted the resignation of Defense Minister Kim Yong Hyun, who initially proposed the idea of declaring martial law – according to both the impeachment filings and one senior military official.

Yoon has nominated Choi Byung-hyuk, a retired four-star general and currently South Korea's ambassador to Saudi Arabia, as a replacement.

The finance, education and justice ministers are also planning to resign from their posts, according to Yonhap.

The moves come 24 hours on from a night of chaos in Seoul when Yoon took the unprecedented decision to declare martial law, only to lift it a few hours later following a unanimous vote by the National Assembly.

The vote took place in an emergency midnight sitting as parliamentary aides kept armed troops out of the chamber using furniture blockades and fire extinguishers.

'Political suicide'

On Wednesday, US Deputy Secretary of State Kurt Campbell said that Yoon had made a serious misjudgment.

"This is a powerful symbol of the fact that people were prepared to come out and make clear that this was a deeply illegitimate process," he said. "One that would be met by the will of the people, and frankly, the will of the legislative bodies."

One analyst told the Associated Press that Yoon's actions were "political suicide."

mf/kb (AP, Reuters, dpa, AFP)