LONDON — U.K. Deputy Prime Minister David Lammy will meet U.S. Vice President JD Vance in Washington Thursday as European leaders try to pin down security guarantees for Ukraine.

Lammy will travel to D.C. Wednesday to take part in celebrations marking the 250th anniversary of the founding of the United States, but will revive some old connections on his trip.

The meeting comes at a particularly sensitive time for U.S.-U.K. relations after U.S. President Donald Trump doubled down on his claims to Greenland following a U.S. operation to capture Venezuelan President Nicolás Maduro. U.K. Prime Minister Keir Starmer, and other European leaders, issued a statement Tuesday warning the Danish-held territory’s security must be ensured collectively by NATO.

The pair are expected to discuss Ukraine alongside other topics at their latest meeting, according to three British officials and one U.S. official familiar with their plans, not authorized to speak on the record.

Lammy, Britain’s former foreign secretary, has developed a friendship with the American vice-president. It saw Vance and his family stay with Lammy during a holiday to the U.K. last summer. The two men have bonded over their difficult upbringings as well as their faith, with Lammy attending Mass in Washington at the vice-president’s invitation in March 2025.

Lammy was moved from the post of U.K. foreign secretary in a cabinet reshuffle last September to become justice secretary as well as the prime minister’s deputy, following the resignation of Angela Rayner.

While in the U.S. he is also expected to meet members of Congress with whom he has good ties, in what one of the British officials quoted above described as “a long-planned trip to discuss the special relationship.”

The visit will nonetheless form part of London’s efforts to cement American backing for any ceasefire negotiated between Ukraine and Russia, currently being hammered out at a meeting of the “coalition of the willing” in Paris.

Vance was previously seen as one of the most skeptical voices in the White House on the U.S. role in seeking peace for Ukraine, but became more directly involved in talks in the second half of last year.