Last Friday, the European Union green-lit a trade agreement with the South American customs union Mercosur. The deal paves the way for the creation of one of the world’s largest free trade zones in terms of population, encompassing more than 700 million people. After 25 years of on-and-off negotiations , the timing of the EU’s approval underscores the compact’s geopolitical significance. The agreement, which is due to be signed in Paraguay on Jan. 17, comes just as Washington is embracing a