It looks like for the next year USFK can count on maintaining a troop strength of at least 22,000 personnel:
President Donald Trump has objected to a series of provisions in the newly passed 2019 National Defense Authorization Act, including limits on the reduction of troops in South Korea and recognizing Crimea as a Russian province.
The defense legislation, which Trump signed into law Monday, sets new restrictions to keep the administration from decreasing troops in South Korea to less than 22,000. It also prohibits U.S. funds from helping legitimize Russia’s control of Crimea.
Both provisions, among several others in the NDAA, reflect congressional concerns about the president and drew objections from the White House. [Stars & Stripes]
You can read more at the link.