The two nations also share a close economic relationship, with the U.S being South Korea's second largest trading partner, receiving $66 billion in exports in 2016. In 2007, a free trade agreement known as the Republic of Korea-United States Free Trade Agreement (KORUS FTA) was signed between South Korea and the United States, but its formal implementation was repeatedly delayed, pending approval by the legislative bodies of the two countries. On 12 October 2011, the U.S. Congress passed the long-stalled trade agreement with South Korea. It went into effect on 15 March 2012.