Opposition parties in South Korea submitted a motion on Wednesday to impeach President Yoon Suk Yeoul, who is facing mounting calls to step down after he imposed a short-lived martial law order which thrust the country into political turmoil. Impeaching Yoon would require the support of two-thirds of the parliament and the backing of at least six of the country's Constitutional Court judges. Speaker of the Assembly Woo Won-sik is set to open a session for the motion to be debated, which could happen as early as in two days. Yoon's senior advisers and secretaries offered to resign collectively and his Cabinet members, including Defence Minister Kim Yong Hyun, also faced calls to step down, as the nation struggled to make sense of what appeared to be a poorly-thought-out stunt. Yoon abruptly imposed martial law on the country in a televised address on Tuesday, vowing to eliminate "anti-state" forces. He accused the nation's opposition of sympathising with North Korea and said martial law would help "rebuild and protect" the country from falling into ruin. "I will eliminate anti-state forces as quickly as possible and normalize the country," he said, while asking the people to believe in him and tolerate "some inconveniences." After his declaration, 190 lawmakers of South Korea's parliament forcibly entered the shuttered building to vote down the decree, which was formally lifted in the early hours of Wednesday morning, just six hours after Yoon passed it. The liberal opposition Democratic Party, which holds a majority in parliament, called Yoon's declaration illegal and demanded he take steps to resign. "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" the party said in a statement. If Yoon is impeached, he'll be stripped of his constitutional powers until the Constitutional Court can rule on his fate, with the country's Prime Minister Han Duck-soo, taking over his presidential responsibilities. As calls mounted for Yoon's Cabinet to resign, Han issued a public message pleading for patience and calling for Cabinet members to "fulfill your duties even after this moment." South Koreans reacted with shock to Yoon's decision, which is the first time martial law has been declared in the Asian democracy for nearly 50 years. 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 maintain peace and order. It is questionable whether South Korea, a functioning and relatively peaceful democracy, is currently in such a state. When martial law is declared, "special measures" can be employed to restrict freedom of press, freedom of assembly and other rights, as well as the power of courts. Following Yoon's announcement, South Korea's military said that parliament and other political gatherings that could cause "social confusion" would be suspended, according to local media. The military said anyone who violated the decree could be arrested without a warrant. In Washington, the White House said the US was "seriously concerned" by the events in Seoul, with a spokesperson for President Joe Biden's administration adding that they were not informed in advance of Yoon's decision and were in contact with the South Korean government. Yoon — whose approval rating dipped in recent months — has struggled to push his agenda against an opposition-controlled parliament since taking office in 2022. His government has particularly been locked in an impasse with the opposition over next year's budget bill. During his televised announcement, Yoon also described the opposition as "shameless pro-North Korean anti-state forces who are plundering the freedom and happiness of our citizens." He did not elaborate. — Euronews