SEOUL, South Korea — South Korea’s Constitutional Court ruled on Monday to strike down the impeachment of Prime Minister Han Duck-soo and restore his powers, marking the latest twist in the country’s political turmoil after his impeachment as acting president more than two months ago.

Han took over as acting leader from President Yoon Suk Yeol, who was himself impeached over his short-lived declaration of martial law last year.

Prime Minister Han lasted less than two weeks in the…