A deepening political crisis in South Korea has not diminished the military readiness of 28,500 troops stationed in the Asian state, a U.S. official said on Friday, but Washington is closely monitoring the situation.

South Korea's acting President Han Duck-soo has been impeached by the opposition party controlling the National Assembly. This comes weeks after President Yoon Suk Yeol's imposed martial law, leading to his own impeachment.

SEOUL—South Korea’s legislature voted to impeach acting President Han Duck-soo on Friday after he declined to make judicial appointments needed to advance the impeachment of his predecessor, extending the political upheaval that began with a short-lived martial law declaration earlier this month.