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.

Shares of South Korean automakers Hyundai Motor and Kia Corp fell on Thursday after U.S. President Donald Trump said the U.S. will charge a 15% tariff on imports from South Korea, including autos, as part of a trade deal.

The agreement that Japan secured has added pressure on South Korea to defuse the threat of high tariffs on its exports to the United States.