-Yoon to face deepening political isolation amid growing threats of impeachment

-All senior aides, Cabinet members offer to resign

-Opposition submits bills to impeach Yoon, defense minister

-Offering to resign, defense minister apologizes, says will take sole responsibility

-Ruling party, PM convene at presidential office, PPP split on severing ties with Yoon

-Supreme Court chief justice says illegality of martial law declaration will be reviewed

-Armed troops forcibly enter Assembly for 1st time in history of legislature

-Constitutional Court faces 3 vacancies, requires at least 1 new judge for impeachment proceeding

South Korea was thrown into unexpected turmoil after President Yoon Suk Yeol's abrupt declaration of emergency martial law late Tuesday evening prompted the main opposition to push for his immediate impeachment and the ruling party to mull cutting off ties with the embattled leader.

Despite Yoon having backed down earlier than expected, the damage of the six-hour chaos was done. Videos of martial law troops breaking and entering the National Assembly, a symbol of democracy here, while carrying guns as the parliamentary aides fought back by spraying fire extinguishers, sent shock waves through the nation.

The opposition says impeaching Yoon is now a must.

The Democratic Party of Korea and five other opposition parties on Wednesday afternoon submitted a bill to impeach the president with the aim of having it passed between Friday and Saturday. The main opposition plans to table the bill at the plenary session scheduled around midnight.

The main opposition also proposed an impeachment bill for Defense Minister Kim Yong-hyun. Impeachment bills need to be put to vote within 72 hours of their submission to the plenary meeting. The defense minister said he has offered to resign.

Kim said all members of the country’s armed forces who were mobilized while the martial law was in effect were acting under his direction, and that he alone was solely responsible for all that happened.

Kim apologized to the South Korean people for the chaos and confusion caused by the martial law.

In a joint statement, the parties said the president has “opened the door to his impeachment himself with the martial law fiasco he pulled.”

The calls for impeaching Yoon are seeing a new momentum outside the Assembly.

The Democratic Party was joined by a large crowd of supporters as they rallied on the steps of the Assembly main building at around noon Wednesday, calling on Yoon to step down.

They held signs and chanted slogans like “Impeach Yoon” and “Time to let him go” for about an hour in the chilly December cold.

Main opposition leader Lee Jae-myung said that Yoon is the kind of a leader that "could launch a limited war (on the Korean Peninsula) if he deems emergency martial law involving armed forces as ineffective," during the rally.

He raised the possibility of Yoon declaring martial law for a second time, which could provoke North Korea.

"(Because) Yoon could declare martial law again due to his recent failure, we now face a bigger risk. There is a bigger danger that (the second decree) could provoke North Korea and disturb the military demarcation line which could end up in an armed conflict," Lee explained.

For the past month, the Democratic Party has been staging a rally every Saturday to impeach Yoon without much success in getting people to join in.

The day after the martial law declaration, a wave of spontaneous protests erupted across the country to denounce the president.

In major cities including Busan, Daegu, Gwangju, Sejong and Jeju, candlelight rallies were announced, invoking a series of protests held in 2016 that led to the impeachment of former President Park Geun-hye.

According to the Democratic Party, the main opposition leader Rep. Lee Jae-myung and his ruling party counterpart Han Dong-hoon have held a discussion concerning the president’s impeachment.

“We talked a little bit about (the impeachment bill) earlier at the plenary meeting,” Lee told reporters early Wednesday.

With the threat of impeachment looming over his head, Yoon's decree of martial law, which hands extra powers to the military and has historically allowed presidents to gain tight control of political activities and the media, is likely to backfire on him, an expert said. The move will propel him into a deeper political isolation, with his supporters within the ruling conservative People Power Party turning their backs on him, while the main opposition Democratic Party of Korea gears up for his impeachment.

“Strong signs of Yoon’s political isolation have existed for some time, but his declaration of martial law is projected to leave him more stranded,” Park Won-ho, professor of political science and international relations at Seoul National University said via phone.

“His party members (including People Power Party Chair Han Dong-hoon) are asking him to leave the party, so this means he has lost a large chunk of his political shield. The fact that 190 of the 300-member parliament unilaterally voted in favor of the motion to end martial law enforcement means that a strong majority of the Assembly has decided not to side with him,” he added.

The ruling bloc on Wednesday was heavily divided over Yoon’s decree, with several expressing opposition to the declaration of martial law.

Han, the leader of the ruling People Power Party, said the president declaring martial law was “flat out wrong.” He added that defense chief Kim Yong-hyun, who was pointed as having advised the president on imposing military rule, needed to be removed from the post. The ruling party leadership also voiced the need for the entire Cabinet to resign.

All Cabinet members and President Yoon Suk Yeol's aides offered to step down from the post in the aftermath of the six-hour fiasco triggered by Yoon's surprise decree.

Prime Minister Han Duck-soo discussed these matters with leaders of the ruling People Power Party and Yoon aides at an emergency meeting at 2 p.m. at the Prime Minister's office in Jongno-gu, Seoul. The closed-door meeting lasted for about 1 1/2 hours.

Attending the meeting were Han, Minister of Government Policy Coordination Bang Ki-sun, People Power Party Chair Han and his chief secretary Rep. Park Jeong-ha, as well as Yoon's Chief of Staff Chung Jin-suk and Senior Secretary for Political Affairs Hong Chul-ho.

Prime Minister Han and People Power Party leader Han went to the presidential office in Yongsan-gu, Seoul at around 5 p.m.

Neither the Prime Minister's Office, the ruling party nor the presidential office has made an announcement regarding the outcome of the meeting, as of press time.

All of Yoon's aides, including Chief of Staff Chung, Director of National Policy Sung Tae-yoon and National Security Adviser Shin Won-sik, as well as 11 senior secretaries, offered to resign from their posts, according to the presidential office Wednesday morning. The decision came after Chung presided over a closed-door meeting of senior secretaries.

It was the second time Yoon aides offered to do so, since the ruling bloc's crushing defeat in the April general election. Back then, Yoon replaced a few of them -- then-Chief of Staff Lee Kwan-sup and then-senior secretary for political affairs Han O-sub.

At a separate meeting hosted by Prime Minister Han at 11 a.m., all members of the Cabinet, including 18 ministers of the government, offered to step down from their posts.

Rep. Lee Jun-seok, a former People Power Party leader, likened Yoon to a dictator in a Facebook post Wednesday.

Lee said the democracy of South Korea was “briefly threatened by the actions of a scoundrel with extremist views,” referring to the president.

An impeachment motion requires at least 200 or two-thirds of the 300-member Assembly to vote in favor of the impeachment motion for it to be forwarded to the Constitutional Court, which has the authority to finalize the proposal.

The Constitutional Court Act states that to uphold an impeachment motion, it requires at least seven of the nine justices to review and carry out a trial on the case. Then six of the nine justices of the Constitutional Court have to vote in favor of the motion. At the moment, there are only six justices as the assembly has yet to elect the successors to replace three recently retired justices.

Regarding whether it would be "difficult" for the main opposition to pursue Yoon's impeachment under the current Constitutional Court, Cho responded that the Democratic Party plans to request the prime minister, who would serve as the leader in acting capacity, when the president's power is suspended to help appointment of the remaining three justices.

The latest martial law decree, which involved armed troops forcibly entering the Assembly for the first time in Constitutional history, could lead to Yoon getting charged for treason or insurrection, according to legal experts.

"If the troops forcibly entered the Assembly and obstructed or prevented the decision making process of the parliament, then (Yoon) could be charged with insurrection or treason," Lim Ji-bong a professor at Sogang University Law School said.

Article 87 of the Criminal Act states that a "person who creates violence for the purpose of usurping the national territory or subverting the Constitution shall be punished."

The Constitution states that the president shall not be charged with a criminal offense during his tenure of office except for insurrection or treason.

Chief Justice of the South Korean Supreme Court Cho Hee-dae told reporters on Wednesday that the Supreme Court will review the procedures that were followed in Yoon's decree, affirming that the judiciary will “steadfastly fulfill its role during challenging times.”

“The judiciary will ensure its role as the ultimate protector of the citizens’ rights and freedoms, and will work to alleviate any concerns about judicial independence and integrity,” affirmed Cho.

When asked about procedural irregularities in Yoon’s declaration of martial law, such as the lack of Cabinet approval or proper notification being made to high-ranking political officials prior to the proclamation, Cho stated that the judiciary will “observe what procedures were followed” in order to address the matter at a later date.

Regarding questions about whether the sudden declaration of martial law could be grounds for impeachment, Cho commented, “I will address that in due course.” Following the six-hour martial law declaration, the opposing Democratic Party said Wednesday that its lawmakers will call on Yoon to step down from his position or they will take steps to impeach him.