SEOUL—After four months of political uncertainty, South Korea has some clarity about its future, following the dismissal of impeached President Yoon Suk Yeol over his short-lived declaration of martial law.

The stakes are especially high now for the U.S. ally that is home to America’s largest overseas military base. The country faces economic stress due to the Trump administration’s new tariffs, rising tension with North Korea and a sharp partisan divide among the public.