A couple of long-standing trade disputes saw new actions on Monday.
The World Trade Organization ruled that a new European Union tariff on imported bananas violates international agreements.
Nine Latin American nations said the $279-a-ton levy would seriously harm their ability to export the fruit.
In a separate WTO case, Japan said it will slap 15 percent levies on U.S.-made steel imports at the beginning of September.
The move could cost American industry up to $50 million, and is retaliation for U.S. measures that the WTO has said unlawfully protected the U.S. steel industry.
Washington placed tariffs on certain steel products from Japan, Brazil and other nations several years ago, amid allegations that those nations sold their products at unfairly low prices.
Some information for this report provided by AP, AFP and Reuters.