South Korea’s Opposition parties Wednesday submitted a motion to impeach President Yoon Suk Yeol over the shocking and short-lived martial law that drew heavily armed troops to encircle the parliament before lawmakers climbed walls to reenter the building and unanimously voted to lift his order.

Impeaching Yoon would require the support of two-thirds of the parliament, and at least six justices of the nine-member Constitutional Court would have to endorse it to remove him from office. The motion, submitted jointly by the main liberal Opposition Democratic Party and five smaller Opposition parties, could be put to a vote as early as Friday.

Yoon’s senior policy advisers and defence minister Kim Yong Hyun offered to resign as the nation struggles to make sense of what appeared to be a poorly-thought-out stunt. The Democratic Party on Wednesday submitted a separate motion to impeach Kim, who it alleged recommended the martial law declaration to Yoon.

In his speech announcing the abrupt order on Tuesday night, Yoon vowed to eliminate “anti-state” forces and continued to criticise the Democratic Party’s attempts to impeach key government officials and senior prosecutors. But martial law lasted only about six hours, as the National Assembly voted to overrule Yoon before his cabinet formally lifted it around 4.30am.

The Democratic Party, which holds a majority in the 300-seat parliament, said on Wednesday that its lawmakers had decided to call on Yoon to quit immediately or they would take stepsto impeach him.

“President Yoon Suk Yeol’s martial law declaration was a clear violation of the Constitution. It didn’t abide by any requirements to declare it,” a party statement said. “His martial law declaration was originally invalid and a grave violation of the Constitution. It was a grave act of rebellion and provides perfect grounds for his impeachment.”

Impeaching him would require support from 200 of the National Assembly’s 300 members. The Democratic Party and other small Opposition parties together have 192 seats. But the rejection of Yoon’s martial law declaration in a 190-0 vote included the votes of 18 lawmakers from Yoon’s ruling People Power Party, according to National Assembly officials. PPP leader Han Dong-hun and Seoul mayor Oh Se-hoon, also a member, criticised Yoon’s martiallaw declaration.

Cho Jinman, a professor at Seoul’s Duksung Women’s University, said it’s highly likely that lawmakers will back Yoon’s impeachment motion given that some from the ruling party already voted down his edict.

If Yoon is impeached, he’ll be stripped of his constitutional powers until the Constitutional Court rules. Prime Minister Han Duck-soo, the No. 2 position in the South Korean government, would take over his presidential responsibilities. Han issued a public message pleading for patience and calling for cabinet members to “fulfill your duties even after this moment”.

Cho Jinman, a professor at Seoul’s Duksung Women’s University, said it’s highly likely that lawmakers will back Yoon’s impeachment motion given that some from the ruling party already voted down his edict.

If Yoon is impeached, he’ll be stripped of his constitutional powers until the Constitutional Court rules. Prime Minister Han Duck-soo, the No. 2 position in the South Korean government, would take over his presidential responsibilities. Han issued a public message pleading for patience and calling for cabinet members to “fulfil your duties even after this moment”.

The Constitutional Court has only six incumbent justices following three retirements. That means all six must approve Yoon’s possible impeachment motion for it to succeed. They include those appointed after Yoon took office, so the Democratic Party is expected to speed up the process of exercising its rights to recommend two of the three new justices.

Yoon’s martial law declaration, the first of its kind in more than 40 years, harkened to South Korea’s past military-backed governments when authorities occasionally proclaimed martial law and other decrees that allowed them to station combat soldiers, tanks and armoured vehicles on streets or at public places like schools to prevent anti-government demonstrations. Such scenes of military intervention had not been seen since South Korea achieved a democracy in the late 1980s until Tuesday night.

After Yoon’s declaration, troops carrying full battle gear, including assault rifles, tried to keep protesters away from the National Assembly as military helicopters flew overhead and landed nearby. One soldier pointed his assault rifle at a woman who was among protesters outside the building demanding that the martial law be lifted.

It wasn’t clear how the 190 lawmakers were able to enter a parliamentary hall to vote down Yoon’s martial law decree. Opposition leader Lee Jae-myung and National Assembly Speaker Woo Won Shik were seen climbing over walls. As troops and police officers blocked some from entering, they didn’t aggressively restrain or use force against others.

No major violence has been reported. The troops and police personnel were later seen leaving the grounds of the National Assembly after the parliamentary vote to lift the martial law. Woo said: “Even with our unfortunate memories of military coups, our citizens have surely observed the events of today and saw the maturity of our military.”

Under South Korea’s Constitution, the President can declare martial law during “wartime, war-like situations or other comparable national emergency states” that require the use of military force to restrict the freedom of press, assembly and other rights to maintain order. Many observers question whether South Korea is currently in such a state.

The Constitution also states that the President must oblige when the National Assembly demands the lifting of martial law with a majority vote. A presidential official said that Yoon decided to impose martial law as a way to resolve a political deadlock and did it in the middle of the night to minimise its negative impacts on the economy. The official requested anonymity to discuss the sensitive nature of the issue.

Some experts say Yoon clearly violated the Constitution in how he imposed martial law. While martial law allows “special measures” to restrict individual freedoms and the authority of agencies and courts, the Constitution does not permit the functions of the parliament to be restricted. But in following Yoon’s declaration on Tuesday, South Korea’s military proclaimed parliamentary activities were suspended and deployed troops to try to block lawmakers from entering the National Assembly.

Park Chan-dae, the Democratic Party’s floor leader, called for Yoon to be investigated on charges of rebellion over the way he deployed troops to the parliament.