U.S. Secretary of State John Kerry visits Brussels and London Monday, the first senior U.S. official to visit either location since the British vote last week to leave the European Union in a move that is of great concern in Washington.
U.S. officials say will express U.S. support for Britain and stress the importance of other EU members remaining in the bloc.
He said Sunday the U.S. regrets the "Brexit" vote, but vowed to continue a close relationship with EU.
His talks in Brussels come amid a flurry of top-level diplomatic activity Monday, including the leaders of European powers Germany, France and Italy getting together to discuss what's next now that Britain is pulling out.
Kerry is then heading to London to meet with British Foreign Secretary Philip Hammond and other officials.
British Finance Minister George Osborne said Monday that "the fundamentals of the British economy are strong" and Britain will "provide stability in these challenging times."