Biden in Europe: Live Updates

It was only two years ago, in the heat of the United States presidential election campaign, that President Biden called Prime Minister Boris Johnson of Britain a “physical and emotional clone” of President Donald J. Trump.

He did not mean it as a compliment.

But now, as the two stewards of the “special relationship” between Britain and the United States prepare to meet face to face for the first time since Mr. Biden took office, they will stress the enduring strength of the alliance.

They are expected to emphasize a joint vision for a sustained global recovery from the pandemic and will evoke the two nations’ powerful shared history to drive home the point.

Mr. Biden and Mr. Johnson are expected to announce what is being billed as a renewal of the Atlantic Charter — the declaration of post-war cooperation that Prime Minister Winston Churchill and President Franklin D. Roosevelt laid out in 1941 during World War II.

Still, the fundamental issues that divide them remain.

Mr. Biden opposed Britain’s drive leave the European Union, a push that Mr. Johnson helped lead. The American president is also concerned about Northern Ireland, since the Brexit deal has inflamed tensions and threatened to reignite sectarian tensions.

“President Biden has been crystal clear about his rock-solid belief in the Good Friday Agreement as the foundation for peaceful coexistence in Northern Ireland,” the White House national security adviser, Jake Sullivan, told reporters aboard Air Force One on Wednesday, referring to the 1998 accord that helped bring about peace in the territory, which is part of the United Kingdom.

Mr. Biden and Mr. Johnson will meet on Thursday afternoon at Carbis Bay in Cornwall, before Friday’s meeting of Group of 7 leading industrial nations.

It is the start of a whirlwind weeklong tour that includes meetings with Queen Elizabeth II on Sunday, NATO officials and European Union leaders next week, plus a summit with President Vladimir V. Putin of Russia.

Mr. Biden began his first overseas trip as president on Wednesday evening by telling United States troops in Britain that the world’s future depended on restoring the longstanding alliances with Europe that have been “hardened in the fire of war” and built by “generations of Americans.”

Speaking to troops at R.A.F. Mildenhall, he called his weeklong diplomatic overture “essential,” saying that no nation acting alone could meet the world’s challenges. But he also vowed to stand up to adversaries like China and Russia, pledging to tell Mr. Putin “what I want him to know.”

On the eve of meeting with European leaders rattled by Russia’s aggressive movement of troops along Ukraine’s borders, Mr. Biden pledged to “respond in a robust and meaningful way” to what he called “harmful activities” conducted by Mr. Putin.

Mr. Biden also cast his trip in broader terms as an effort to rally the United States and its allies in an existential struggle between democracy and autocracy.

“I believe we’re in an inflection point in world history,” Mr. Biden said, “a moment where it falls to us to prove that democracies not just endure, but they will excel as we rise to seize enormous opportunities in the new age.”

One of the toughest issues President Biden is expected to take up this week with Prime Minister Boris Johnson of Britain is the status of Northern Ireland, where Brexit-fueled tensions threaten the return of lethal sectarian violence.

The 1998 Good Friday Agreement ended the Troubles, the 30-year guerrilla war between Catholic nationalists seeking unification with the Republic of Ireland and predominantly Protestant unionists, who want to stay in the United Kingdom. The border between Ireland and Northern Ireland virtually disappeared, allowing unfettered movement of people and commerce.

But now, a part of London’s Brexit deal with Brussels is inflaming resentment among unionists. To avoid resurrecting a hard border with Ireland — an unpopular idea on both sides of the boundary — the Northern Ireland Protocol requires checks on goods flowing between the North and the rest of the United Kingdom.

Creating a commercial border between Northern Ireland and the rest of the country violates promises made by the British government and imposes an economic and psychological cost. Northern Irish people who want to remain in Britain feel betrayed, and there have been violent protests against the protocol.

“It has hit the community here like a ton of bricks that this is a separation of Northern Ireland from the rest of the United Kingdom,” said David Campbell, chairman of the Loyalist Communities Council, which represents paramilitary groups that some say are stirring up unrest.

Mr. Biden has warned Mr. Johnson, who campaigned for Brexit and negotiated the deal with Brussels, not to do anything to undermine the Good Friday Agreement. He is also mulling the appointment of a presidential envoy for Northern Ireland.

“That agreement must be protected, and any steps that imperil or undermine it will not be welcomed by the United States,” Jake Sullivan, the president’s national security adviser, told reporters on Air Force One on Wednesday.

Asked whether Mr. Johnson had taken steps to imperil the agreement, Mr. Sullivan said: “President Biden is going to make statements in principle on this front. He’s not issuing threats or ultimatums.”

President Donald J. Trump embraced Mr. Johnson and Brexit, but Mr. Biden has been cooler to both. The new president is also a Roman Catholic and devoted Irish-American, fueling speculation that he will be more favorable to the Irish nationalist cause.

As it has with nearly every other major event of the past year, the pandemic looms large over this week’s Group of 7 summit, with world leaders already making commitments to do more to stop the coronavirus as they prepare for the three-day gathering that begins on Friday.

In recent months, wealthy nations with robust vaccination campaigns have quickly moved toward inoculating large swaths of their population. Now, they are pledging to help the rest of the world meet that goal, too.

In a statement released on Thursday, Prime Minister Boris Johnson, who is playing host to the summit as Britain takes up the G7 presidency this year, said it was crucial to use the moment to act.

“The world needs this meeting,” he said. “We must be honest: International order and solidarity were badly shaken by Covid. Nations were reduced to beggar-my-neighbor tactics in the desperate search for P.P.E., for drugs — and, finally, for vaccines,” he added, referring to personal protective equipment.

He said now was the time to “put those days behind us.”

“This is the moment for the world’s greatest and most technologically advanced democracies to shoulder their responsibilities and to vaccinate the world, because no one can be properly protected until everyone has been protected,” he added.”

President Biden, under pressure to address the global coronavirus vaccine shortage, will announce on Thursday that his administration will buy 500 million doses of the Pfizer-BioNTech vaccine and donate them among about 100 countries over the next year, the White House said.

“We have to end Covid-19, not just at home, which we’re doing, but everywhere,” Mr. Biden told United States troops at R.A.F. Mildenhall in Suffolk, England, on Wednesday evening. “There’s no wall high enough to keep us safe from this pandemic or the next biological threat we face, and there will be others. It requires coordinated multilateral action.”

Pfizer said in a statement announcing the deal on Thursday that the United States would pay for the doses at a “not for profit” price. The first 200 million doses will be distributed by the end of this year, followed by 300 million by next June, the company said. The doses will be distributed through Covax, the international vaccine-sharing initiative.

“Fair and equitable distribution has been our North Star since Day One, and we are proud to do our part to help vaccinate the world, a massive but an achievable undertaking,” Albert Bourla, Pfizer’s chief executive, said in a statement.