Why did President Yoon Suk Yeol resort to martial law?

South Korean President Yoon Suk Yeol’s declaration of emergency martial law on Tuesday has sparked widespread criticism, marking the first time in over 40 years that such a measure has been invoked. Political experts suggest that the unprecedented move is rooted in Yoon’s increasing political isolation, compounded by numerous scandals, legislative gridlock and growing tensions with both opponents and allies.

Park Chang-hwan, a political commentator and professor at Jangan University, described the martial law declaration as “a frantic last-ditch effort.” He argued that Yoon’s mounting conflicts and diminishing political support likely drove him to make what Park called “extreme choices.”

“The fact that the president declared martial law without consulting his advisors shows an apparent psychological state of isolation. When people feel cornered, they tend to make absurd decisions,” Park said.

Yoon has faced intense pressure in recent weeks, with the opposition-controlled National Assembly set to vote on a motion to impeach Choe Jae-hae, chair of the Board of Audit and Inspection, and three key prosecutors. The impeachment motion alleges that the officials failed properly to investigate Yoon’s wife, first lady Kim Keon-hee, over allegations of stock manipulation.

The Democratic Party of Korea, which holds the majority of seats in the National Assembly, has accused Choe and other prosecutors of bias and negligence in their handling of investigations of allegations against the first lady. They also criticized Choe for refusing to provide documents related to the controversial 2022 relocation of the presidential office to Yongsan.

Yoon’s authority as president has been weakened by the opposition’s majority in the legislature, following their landslide victory in the April 10 general election. Since then, Yoon’s administration has struggled to pass its agenda, instead repeatedly vetoing the bills passed by the liberal opposition.

Falling approval, internal conflicts

Yoon’s approval ratings have plummeted to around 17 percent, driven by a series of scandals, including allegations that the first lady accepted gifts such as a luxury Christian Dior bag worth 3 million won ($2,200) and participated in a stock price manipulation scheme. Last month, Yoon issued a public apology but refused to authorize a wider investigation into the allegations, further fueling opposition criticism.

Compounding his troubles, Yoon has reportedly clashed with Han Dong-hoon, chair of the ruling People Power Party and once a key ally. This internal conflict has deepened Yoon’s political isolation, leaving him increasingly embattled.

“Yoon’s growing isolation within his own party and the opposition’s relentless pursuit of accountability have driven him to extreme measures,” Park noted.

In his televised address announcing his martial law decree, Yoon claimed the move was necessary to protect South Korean citizens from “anti-state forces and pro-North Korea followers." He accused his political opponents of paralyzing the government by impeaching key officials and obstructing his administration’s agenda.

“I will eradicate anti-state forces and normalize the country as soon as possible,” Yoon declared. Critics argue that Yoon’s rhetoric is an attempt to frame the opposition as enemies of the state, further polarizing the already divided political landscape.

Political observers warn that Yoon’s use of martial law could set a dangerous precedent, undermining democratic norms and eroding public trust.

The last time martial law was declared in South Korea was in 1979, during a military coup following the assassination of President Park Chung-hee. The measure has not been invoked since South Korea transitioned to a parliamentary democracy in 1987, making Yoon’s decision all the more controversial.