South Korean president dismisses defense minister after failed martial law declaration

SEOUL and LONDON -- As the opposition's effort to impeach South Korean President Yoon Suk Yeol made its way through the National Assembly, the leader accepted the resignation of Defense Minister Kim Yong Hyun, dismissing a key ally in his brief failed imposition of martial law.

Opposition lawmakers had moved on Wednesday to impeach the president, submitting a motion a day after Yoon's late-night declaration roiled the nation and set off hours of political turmoil. The motion to impeach was submitted by 191 lawmakers.

It is expected to make its way through the National Assembly in the coming days, with a vote likely either Friday or Saturday. The measure would require a two-thirds majority to pass. It would then be sent to South Korea's Constitutional Court, which would have to approve the impeachment.

Yoon's party, the conservative People Power Party, controls 108 seats in the 300-member National Assembly, meaning some would have to break with their party for the impeachment vote to succeed.

As he declared martial law in a televised speech late Tuesday, the president said the measure would be necessary due to the actions of the Democratic Party, a liberal coalition that Yoon accused of controlling parliament, sympathizing with North Korea and paralyzing the government.

The declaration included banning political activities, including rallies and protests. Yoon also called for a stop to the "dissemination of fake news" and the manipulation of public opinion. All press would have been controlled by the state under the declaration.

The declaration was met with protests and a swift vote in the National Assembly, with the 190 members on hand unanimously voting to lift Yoon's martial law order. Within hours, Yoon had backtracked, and the State Council convened to vote to officially lift the order.

Secretary of State Antony Blinken said on Wednesday that the U.S. was not aware of Yoon's plan before his declaration. "For us, this is one of the most critical alliances that we have anywhere in the world," Blinken said during a visit to NATO headquarters in Belgium. "South Korean democracy, it’s one of the most powerful stories anywhere in the world."

"It’s very important that any disputes, differences, political differences be resolved peacefully and pursuant to the rule of law," Blinken added. "That’s what we’re seeing now. That’s what’s so important to sustain."

Defense Secretary Lloyd Austin also called off a trip to South Korea on Thursday that was planned to follow his participation in the Reagan National Defense Forum in Simi Valley, California, this week, a U.S. military official confirmed to ABC News.

Yoon began his five-year term in May 2022 after wining office by a razor-thin margin.

Kim, the defense minister, had only recently taken up his post.

He had served as the head of Presidential Security Services in Yoon’s administration, before becoming a cabinet member in September, according to Yonhap News Agency. He’s a retired three-star Army general.

As opposition lawmakers worked to impeach Yoon, public calls for the president's resignation continued. Crowds again gathered in Seoul on Thursday, holding another candlelit vigil in support of Yoon's ouster in front of the National Assembly building.

ABC News' Will Gretsky, Ellie Kaufman, Joe Simonetti, Meredith Deliso and Matt Seyler contributed to this report.