Britain and the EU are in a spat over post-Brexit trade arrangements that could see British sausages banned from entering Northern Ireland, the only part of the UK that borders the 27-nation bloc.
Brussels has been angered by London's failure to introduce checks on goods heading across the Irish Sea from the mainland UK to the province of Northern Ireland.
Johnson met the bloc's leaders, European Commission President Ursula von der Leyen and European Council President Charles Michel.
The row centers on provisions of the Brexit deal that essentially created a regulatory border between Northern Ireland and the rest of the United Kingdom.
Antony Blinken said any deal would take “some time” and that U.S. President Joe Biden wants to ensure any trade agreement would benefit American workers and their families.
The deal, which was finalized on Christmas Eve, had already been ratified by the U.K.
The two sides are trying to find common ground on trade rules in Northern Ireland, where Britain’s exit from the EU has unsettled a delicate political balance.
India is categorised as an international actor of growing importance in the review, which commits to achieving an Enhanced Trade Partnership this year.
UK Brexit minister Michael Gove and European Commission Vice President Maros Sefcovic are meeting in London later Thursday to try to smooth out the problems, but few expect a quick resolution.
Under the post-Brexit deal, EU products should still be able to travel unhindered from the bloc to Northern Ireland.