Impeached South Korean President Yoon Suk Yeol was arrested and questioned for hours by investigators in relation to a criminal insurrection probe, ending a weeks-long standoff with authorities.

TOKYO (Kyodo) -- Japan is monitoring developments in South Korea with "particular and grave" concerns, the top government spokesman said Wednesday, following the detention of President Yoon Suk Yeol over his declaration of martial law in December.

A standoff between rival government forces outside the presidential compound in South Korea is a startling development, even for observers used to the country’s famously rough and tumble politics