WASHINGTON—President Trump announced the outlines of an agreement on trade with the U.K. on Thursday, the first in what the White House hopes is a series of deals since imposing tariffs against allies and adversaries.

The Trump administration announced a trade deal with the United Kingdom Thursday in grandiose terms, but with only limited details about what it achieves.

President Donald Trump on Thursday said his administration has made a deal with the U.K. on trade, offering a bit of relief to investors who have spent weeks waiting for such agreements.