It is the latest protectionist trade move by US President Donald Trump.
The United States on Wednesday told South Korea it wants to renegotiate a 2012 free trade agreement, citing a lopsided trading relationship.
It is the latest protectionist trade move by US President Donald Trump.
He wants to overhaul the North American Free Trade Agreement and has threatened tariffs on foreign products, such as steel.
He also withdrew from the 12-nation Trans Pacific Partnership agreement in January.
South Korea is a major US trade partner, with the US exchanging about $144.6bn (£112m) in goods and services with the country last year.
The Obama administration had said the 2012 free trade agreement – described at the time as the most significant in 16 years – would boost US businesses.