South Korea's mainly imports mineral fuels, mineral oils, bituminous substances (25 percent of total imports), electrical machinery and equipment (18 percent), nuclear reactors, boilers, machinery and mechanical (10 percent), optical, photographic, cinematographic, measuring (4 percent), road vehicles (3 percent), iron and steel (3 percent), ores, slag, ash (3 percent), organic chemicals (3 percent), plastics and articles thereof (2 percent), miscellaneous chemicals products (2 percent), and inorganic chemicals, compounds of precious metals (2 percent). China is the biggest source of imports (21 percent of total imports), followed by the US (12 percent), Japan (9 percent), Saudi Arabia, Vietnam, Australia and Germany (4 percent each), Taiwan, Russia and Qatar (3 percent each), and Kuwait, Malaysia, the UAE and Indonesia (2 percent each).