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

Trump delayed the "reciprocal tariffs" in April, vowing to strike roughly 90 trade deals in 90 days. So far, the White House says it has reached trade agreements with only the United Kingdom and Vietnam, as well as a preliminary accord with China.