In recent years, Vietnam has forged strategic and economic links with the United States, its former foe, making the steep tariff rate all the more of a shock.

The U.S. has become the country’s biggest customer, helped by manufacturers moving away from China. Now, its ballooning trade surplus is putting it in President Trump’s sights.

China retaliated against President Donald Trump’s tariffs Friday as the global trade war intensified and stocks fell for a second day. Vietnam, on the other hand, may be ready to negotiate.