The opening salvos of a trade war between the U.S. and China has put North Dakota farmers on the front lines.

Soybean futures tanked by as much as 5 percent last week after China retaliated to President Donald Trump’s tariffs on Chinese goods by slapping a 25 percent tariff on more than 100 products, including soybeans. China set no date for implementation of the soybean tariffs.

China’s retaliatory tariffs are largely aimed at agricultural and rust belt states, where Trump has enjoyed strong support. This is “bringing us closer to a trade war that American producers cannot afford,” said U.S. Sen. Heidi Heitkamp, D-ND.