"Over the past 18 months, the United States and some of its major trading partners have engaged in a contentious 'war' of words over trade--one that has recently tipped over into action, mostly in the form of increased tariffs. The tariffs imposed by the Trump Administration, combined with retaliatory measures adopted by other countries, are reportedly having noticeable effects on trade flows and U.S. businesses. Although the scale and scope of these recent unilateral U.S. tariff increases are unprecedented in modern times, tensions and irritants in international trade relations are not uncommon. Over the last 100 years, the United States has been involved in a number of significant trade disputes. According to the World Trade Organization (WTO), as of August 2018, the United States is currently involved in 271 active trade disputes being addressed in the WTO dispute settlement system--either as complainant or as a respondent. Most disputes are settled, or when unresolved, are contained or defused through bilateral and multilateral negotiations. From the early 20th century until this year, only one resulted in a worldwide tit-for-tat escalation of tariffs: the trade dispute ignited by the U.S. Smoot-Hawley Tariff Act of 1930."
CRS In Focus, IF10958