South Korea’s Justice Ministry today imposed an overseas travel ban on President Yoon Suk Yeol as authorities investigate allegations of rebellion and other charges in connection with his short-lived declaration of martial law last week.

Yoon’s martial law decree last Tuesday, which brought special forces troops into Seoul streets, plunged South Korea into political turmoil and caused worry among its key diplomatic partners and neighbours. On Saturday, Yoon avoided an opposition-led bid to impeach him, with most governing party lawmakers boycotting a parliamentary vote. But the opposition parties vowed to submit a new impeachment motion against him this week.

Bae Sang-up, a Justice Ministry official, told a parliamentary hearing that it banned Yoon from leaving the country following requests by police, prosecutors and an anti-corruption agency as they expand their probes into the circumstances surrounding Yoon’s power grab.

Today, a senior National Police Agency officer told local reporters in a background briefing that police can also detain Yoon if conditions are met. The contents of the briefing were shared with The Associated Press.

While a sitting South Korean president has immunity from prosecution while in office, that does not extend to allegations of rebellion or treason. This means that Yoon can be questioned and detained by police over his martial law decree, but many observers doubt that police will forcefully detain him or search his office because of the potential for clashes with his presidential security service.

In the case of former President Park Geun-hye, who was thrown out of office in 2017 after being impeached by parliament over a corruption scandal, prosecutors failed to search her office and ended up receiving documents outside the compound because presidential officials turned them away.

After refusing to meet with prosecutors while in office, Park underwent questioning by them and was arrested after the Constitutional Court approved her impeachment and ruled to dismiss her as president in March 2017.

The main opposition Democratic Party called Yoon’s martial law imposition “unconstitutional, illegal rebellion or a coup”. It has filed complaints with police against at least nine people, including Yoon and his former defence minister, over the rebellion allegations.

South Korean prosecutors yesterday detained former Defence Minister Kim Yong Hyun, who allegedly recommended that Yoon declare martial law. He became the first person detained in the martial law case.

The Defence Ministry last week separately suspended three top military commanders over their alleged involvement in imposing martial law. They were among those facing the opposition-raised rebellion allegations.

On Saturday, Yoon issued an apology over the martial law decree, saying he won’t shirk legal or political responsibility for the declaration. He said he would leave it to his party to chart a course through the country’s political turmoil, “including matters related to my term in office”.

Since taking office in 2022 for a single five-year term, Yoon, a conservative, has been on a near-constant collision course with his liberal rivals who control parliament. The liberals have introduced a slew of motions seeking to impeach some of his top officials and launched a fierce political offensive against Yoon over a spate of scandals involving him and his wife.

In his martial law announcement on Tuesday night, Yoon called parliament a “den of criminals” bogging down state affairs and vowed to eliminate “shameless North Korea followers and anti-state forces”.

Yoon’s martial law decree lasted only six hours because the National Assembly voted it down, forcing Yoon’s Cabinet to lift it before daybreak Wednesday. Some members of Yoon’s governing People Power Party cast ballots against Yoon’s decree, but the party later decided to oppose his impeachment.

Experts say Yoon’s party fears losing the presidency to liberals in a by-election if he is impeached and ousted, as they did after Park was removed from office.

PPP leader Han Dong-hun said Sunday his party will push for Yoon’s early and orderly exit from office in a way that minimizes social confusion, but he didn’t say when that would happen. He also said Yoon will not be involved in state affairs, including foreign policy.

Critics say Han likely wants to buy time to help his party restore public confidence. His comments on sidelining Yoon from state affairs have also sparked widespread concern and criticism that it violates the constitution.

During today's briefing, the Defence Ministry said Yoon maintains control of the military, a power the constitution explicitly reserves for the president.