Hyundai Motor Co. and affiliate Kia Corp. could face as much as $5 billion in additional costs this year under a new trade agreement between the US and South Korea that imposes a 15% import tariff on automobiles.

Jose Munoz, chief executive officer (CEO) of Hyundai Motor Co., has welcomed a recent tariff deal between South Korea and the United States, saying it provides predictability for the company's long-term business strategy.

Shares in Hyundai and Kia, South Korea's leading automakers, sold off after the country struck a trade pact with the U.S. The country now faces a 15% [tariff on auto exports](