A letter to Bosnia and Herzegovina announcing a 30 percent tariff rate starting on August 1 was mistakenly addressed to “Mr. President,” when the chairperson of the Balkan country’s presidency is a woman.

President Donald Trump unveiled the first in a wave of promised letters that threaten to impose higher tariff rates on key trading partners. But he also suggested that he was still open to additional negotiations and pushed off increased duties until at least August 1.