President Yoon Suk of South Korea reversed his surprise declaration of martial law hours after the decision drove thousands of protesters into the streets and prompted calls for him to resign.

The extraordinary declaration, which President Yoon gave was to counter an opposition that was “trying to overthrow the free democracy,” was the first time a South Korean president had declared martial law since the country’s military dictatorship ended in the late 1980s.

South Korea’s constitution states that the president may proclaim martial law when “required to cope with a military necessity or to maintain the public safety and order by mobilization of the military forces in time of war, armed conflict or similar national emergency.”

President Yoon, who was elected in 2022 and has since been in a near-constant political impasse with the opposition, which controls the National Assembly. Members of the legislature, including those from his own party, voted to repeal the martial law within hours of Mr. Yoon’s declaration.

Army Gen. Park An-Su, who was appointed martial law commander by Mr. Yoon, banned “all political activities,” including political party activities and citizens’ rallies. “All news media and publications are under the control of martial law command,” General Park said.

His edict also banned labor activities and spreading “fake news.” According to South Korean news agency Yonhap, the command ordered all medical staff including trainee doctors, many of whom have been on strike, to return to work in 48 hours. Those who violated the martial law can be arrested without a warrant, the decree said.