In his declaration, Yoon accused the Democratic Party (DPK), which has a majority in the National Assembly, of conducting "anti-state activities" and collaborating with "North Korean communists" to destroy the country, thereby creating a "legislative dictatorship".

At 01:02 on 4 December, 190 legislators who had arrived at the National Assembly Proceeding Hall unanimously passed a motion to lift martial law,[3] despite attempts by the Republic of Korea Army Special Warfare Command to prevent the vote.

It is more widely believed the declaration was motivated by political issues with the DPK-controlled Assembly over repeated impeachment attempts against officials, opposition to his budget, and various scandals involving him and his wife Kim Keon-hee.

[12] On 2 December 2024, the opposition-controlled parliament moved to impeach Board of Audit and Inspection Chair Choe Jae-hae and three prosecutors involved in two scandals surrounding Kim[13] and rejected the government's 2025 budget proposal.

[18] Kim Min-seok, member of the party's Supreme Council, stated "I have well-founded reasons to believe that the conservative Yoon administration is drawing up a contingency plan to declare martial law".

[21] People Power Party floor leader Choo Kyung-ho also denied the possibility of martial law, saying "Such theories ... are no more than scare tactics and propaganda based purely on imagination".

A document was produced in secret by the Defense Security Command (now the DCC) in February 2017 that considered invoking martial law in anticipation of continued street protests if Park Geun-hye was not removed by the Constitutional Court.

[26] Police investigators also found that Defense Intelligence Command chief Major General Moon Sang-ho, his predecessor, Noh Sang-won and two colonels also met at a Lotteria fast food restaurant in Ansan on 1 December to discuss preparations for the declaration.

[38] During police investigations into the martial law declaration, a memo was recovered from a notebook owned by former Army Maj. Gen. Noh Sang-won, former chief of the Defense Intelligence Command, in his residence in Ansan.

[60] and ordered interior minister Lee Sang-min to cut off electricity and water supplies to left-leaning media outlets critical of Yoon, specifically the Hankyoreh, the Kyunghyang Shinmun, MBC and JTBC, as well as the opinion polling agency Flower Research.

[62] A defense ministry report obtained by DPK representative Bak Seung-a stated that around 1,580 troops, 107 military vehicles, 12 Black Hawk helicopters and more than 9,000 rounds of live ammunition were deployed for the implementation of martial law.

[75][76] DCC martial law troops assigned to raid the NEC training center in Suwon questioned their deployment orders, and delayed their arrival by slowing their pace or pulling off at rest stops.

[77] On 9 December, Rep. Lee released a report stating that a DCC brigadier general assaulted a major for questioning deployment orders and forced him on a bus to seize the NEC servers.

[95] On 13 December, a lawyer representing Commissioner Cho said that Yoon had also ordered the arrest of Seoul Central District Court Judge Kim Dong-hyun, who had acquitted Lee Jae-myung of perjury charges in November 2024.

Rebuilding Korea Party leader Cho Kuk called the declaration of martial law "illegal" and said it met conditions for the impeachment of Yoon and Defense Minister Kim.

[117] Former President Moon Jae-in addressed the military as a former commander-in-chief in a Facebook post, urging them to respect the will of the people, not to act against the National Assembly, and to adhere strictly to constitutional principles.

[189] At noon on 4 December, Prime Minister Han Duck-soo held a meeting with Yoon's remaining cabinet members, and party leaders to discuss the fallout of the martial law declaration.

[191] Later on 4 December, all of the major newspapers in South Korea and the National Union of Media Workers unanimously condemned Yoon and called for his arrest, saying the martial law was illegal and an attempted repeat of the brutal coups of the 1980s.

[206] The Center for Military Human Rights Korea also warned of such a possibility, citing the Army restricting leave for some officers and implementing stringent regulations effective until 8 December, which coincided with the period that proposals to impeach Yoon are being discussed in the National Assembly.

[226] The National Archives of Korea issued notices to the Presidential Office, the Defense Ministry and other relevant agencies for the preservation of documents, video footage and other records relating to the declaration of martial law amid concerns over their discarding.

[264] On 8 December, Kim Yong-hyun was arrested on suspicion of committing insurrection by advising Yoon to declare martial law and sending troops into the National Assembly to seize the legislature.

[268] On 9 December, the Ministry of Justice issued an overseas travel ban against Yoon following an investigation into allegations of rebellion linked to his brief imposition of martial law, marking the first instance of a sitting president facing such restrictions.

[288] On 6 February, the defense ministry placed Yeo In-hyung, Lee Jin-woo, Kwak Jong-keun, and Moon Sang-ho on compulsory leave of absence following an ongoing criminal investigation against them over martial law.

[329] On 18 December, the Ministry of National Defense found "at least several dozen soldiers" were at high risk of developing post-traumatic stress disorder (PTSD) and required special care, after conducting psychological evaluations on all personnel dispatched during the martial law incident.

[334] During a press conference in Stockholm on 6 December before delivering her Nobel lecture, 2024 Nobel Prize in Literature laureate, South Korea's Han Kang, who wrote the novel Human Acts inspired by the 1980 Gwangju Uprising, called the martial law declaration a shock, but described sensing the "truthfulness and courage" of "unarmed citizens attempting to stop armed soldiers", "young police and soldiers who moved reluctantly, as if sensing some inner conflict" and "striving to do the least amount of harm as possible".

Unlike past military coups which had the endorsement of the United States, this was mainly a domestic political issue that was handled swiftly and decisively by South Korean citizens without external interference.

Combined with troops refusing to abide by unjust orders, these were cited as reasons to believe that South Korean democracy and society has evolved in the last 4 decades to the point that a return to military rule or dictatorship would not be accepted.

[339] Additionally, a letter signed by 3,000 members of South Korea's film industry, including Parasite director Bong Joon-ho, said the martial law declaration threatened to send the Korean wave "into the abyss".

[340] In the United States, Foreign Policy magazine,[44] the Associated Press,[341] political scientists Sidney Tarrow[342] and Benjamin Engel,[343] and coup historians Joe Wright and John J. Chin[344] described the events as an attempted self-coup.

[373][374] On 11 December 2024, North Korean state media released its first statements on the martial law declaration through an article published in the newspaper Rodong Sinmun,[375] describing it as an "insane act" that was "akin to the coup d'état of the decades-ago military dictatorship era".