President Donald Trump signed an agreement formally lowering some tariffs on imports from Britain as the countries continue working toward a formal trade deal.

U.S. President Donald Trump and British Prime Minister Keir Starmer said Monday that they had signed a trade deal that will slash tariffs on U.K. auto and aerospace industry imports, but they are still discussing how to handle steel production.

The leaders of Britain and the United States announced a deal last month, but it had not been clear when their agreement would go into effect. Britain hailed the announcement as “a huge win.”