Biden Trip to Belfast Stirs Concerns About Slighting Britain’s New King

President Biden plans to visit Northern Ireland next month to mark the 25th anniversary of a landmark peace agreement there. But his trip is stirring concern in diplomatic circles because Mr. Biden will not meet King Charles III, which British and American officials said could be interpreted as a snub, given that he also plans to skip the king’s coronation.

The White House has yet to confirm Mr. Biden’s trip to commemorate the Good Friday Agreement, which ended decades of sectarian violence in Northern Ireland. British and American diplomats with knowledge of the planning said Mr. Biden is scheduled to arrive in Belfast, the capital, on April 11, a week before the king and other leaders are scheduled to gather in the city.

Mr. Biden will spend a day and a half in Belfast, the officials said, before traveling to the Republic of Ireland for three days to explore his ancestral roots. He will be back in the United States before Charles, Prime Minister Rishi Sunak and other leaders, including former President Bill Clinton, are expected to gather in Belfast for a formal ceremony to mark the anniversary.

The president’s heavy emphasis on Ireland, plus the lack of a stop in London or a meeting with the king, has raised concerns among diplomats on both sides about the signal it sends one of America’s closest allies. While Charles remains above politics, he is the head of state, and his coronation is expected to draw a parade of world leaders.

The White House declined to comment publicly on Mr. Biden’s travel, but an administration official said that “details of the trip are still coming together,” and defended the president from suggestions that his actions should cause any offense in Britain.

Mr. Biden’s relationship with the king is “strong,” the official said, noting that the president met with then-Prince Charles and Queen Elizabeth II in Glasgow, Scotland, before her death. The official added that Mr. Biden and his wife attended the queen’s funeral and are sending an official delegation to the coronation on May 6.

The administration official, as well as the officials with knowledge of the planning, spoke on condition of anonymity in order to discuss sensitive matters.

A spokeswoman for Downing Street said, “The prime minister looks forward to welcoming President Biden to the U.K. for commemorations around the anniversary of the Belfast (Good Friday) Agreement in April.” She declined to say whether that meant Mr. Sunak will make an extra trip to Belfast to meet Mr. Biden.

Buckingham Palace did not immediately respond to a request for comment.

Mr. Biden told Mr. Sunak of his intention to visit Northern Ireland when the two leaders met in San Diego this month to inaugurate the next phase of a submarine alliance between the United States, Britain, and Australia, known as AUKUS. He also invited Mr. Sunak to visit Washington in June.

The two men appeared to get along well in San Diego, with Mr. Biden noting that Mr. Sunak is a graduate of the Stanford University business school and gently ribbing him about the fact that he still owns a home in Santa Monica.

“That’s why I’m being very nice to you,” Mr. Biden said. “Maybe you can invite me to your home in California.”

The president had reason to be pleased with Mr. Sunak: He had just struck a deal with the European Union to resolve a dispute over the trade arrangements in Northern Ireland, a thorny legacy of Brexit. Mr. Biden and other officials had pressed successive British leaders to break the impasse with Brussels. The deal, known as the Windsor Framework, paved the way for Mr. Biden to make the visit to Belfast.

The trouble is, if Mr. Biden sticks to this itinerary, he will miss a gathering the following week of leaders, including Mr. Clinton, who was in office at the time the accord was signed, and his wife, Hillary. The product of years of negotiations between Britain, Ireland, and parties in Northern Ireland, the Good Friday Agreement was a diplomatic prize for the Clinton administration long treasured by Democrats in Washington.

For King Charles, the commemoration would have been a highly symbolic place to meet Mr. Biden. That’s particularly true because the president is not planning to attend the coronation. British officials said they were less concerned about Mr. Biden’s lack of attendance at that ceremony, given that he attended the queen’s funeral and has multiple international travel obligations on his calendar.

British officials also stressed that the White House’s planning could still change in ways that would underline the administration’s respect for the new monarch.

Kim Darroch, a former British ambassador to Washington, said a Biden itinerary that excludes the king, and possibly Mr. Sunak, could very well be viewed as a snub, particularly by Britain’s tabloid newspapers.

“If they stick to this, and if they’re not doing it for very good reasons, it’s more evidence of where we stand in Washington,” said Mr. Darroch, though he added, “I suppose the AUKUS summit will be claimed as evidence to the contrary.”

It is not the first time that the Biden administration has ruffled the feathers of its European allies. French officials seethed after the announcement of the submarine alliance because it grew out of secret talks between the United States and Australia that resulted in France being elbowed out of its largest defense contract.

French officials accused Mr. Biden and Secretary of State Antony J. Blinken of blindsiding them, and Mr. Blinken, who spent much of his childhood in Paris and speaks fluent French, was sent to make amends.

Relations between the United States and Britain are generally strong, but some in London note that few American presidents celebrate their Irish roots as unabashedly as Mr. Biden. At a recent St. Patrick’s Day reception with Ireland’s prime minister, Leo Varadkar, Mr. Biden reminisced about his forbears, the Finnegans of Country Louth and the Blewitts of County Mayo. He made clear he was pulling for Ireland to beat England in the six-nations rugby tournament the next day (Ireland won 29 to 16).

“I expect we know — and this is no offense to anyone — but who in the room we’re rooting for,” Mr. Biden joked, a few minutes after recognizing Britain’s ambassador to Washington, Karen Pierce, who was also in the room.