The existing off-base curfew on U.S. troops stationed in South Korea will be extended until early next year to ensure better mission readiness, the commanding unit of the American forces here said Wednesday.The U.S. Forces Korea (USFK) announced that its commander, Army Gen. James D. Thurman, decided to extend the current curfew until Jan. 6. On Oct. 7, Thurman imposed the curfew for 30 days.