Iowa Republican leaders voiced concern Tuesday about a trade war after President Donald Trump upped the trade ante with China, threatening to slap tariffs on another $200 billion of products, the Des Moines Register reported. “We know what happens when tariffs are increased … and there’s retaliation. It hurts agriculture. It’s going to hurt Iowa tremendously,” U.S. Sen. Chuck Grassley said during a weekly call with reporters. Gov. Kim Reynolds said the tariffs threaten a “fragile ag economy.” Sen. Joni Ernst said the “tariffs are nothing more than a tax on Iowa farm families.”