President Trump signed a technology pact with British Prime Minister Keir Starmer on Thursday that boosts joint efforts in artificial intelligence, ushering the countries’ “special relationship” into the 21st century and capping a British sojourn filled with fanfare.

The Technology Prosperity Deal was struck on the second day of Mr. Trump’s state visit, which included a lavish display of ceremony hosted by King Charles III and the royal family.

Several major U.S. tech companies, including Microsoft, will be involved in the deal, which pledged about $42 billion in British investment. Other participating American technology companies include Nvidia, Google, OpenAI and CoreWeave.

Under the partnership, Britain and the U.S. will pool resources and expertise into emerging technologies that can benefit from the best minds and innovations in both nations.

U.S. companies will boost British AI infrastructure with investments in data centers, computer chip manufacturing and other projects.

“The bond between our countries is like no other anywhere in the world,” Mr. Trump said at a joint press conference with Mr. Starmer. “The United States and the United Kingdom have done more good on this planet than any two nations in human history.”

Mr. Trump was greeted by Mr. Starmer and his wife, Victoria, along with a ceremonial guard of honor and bagpipers, upon his arrival at Chequers, a 16th-century manor house near London that prime ministers use as a rural retreat and informal venue for international talks.

Mr. Trump said the leaders would finalize the U.S.-British trade deal “very soon.” He said they found common ground in their dissatisfaction with Russian President Vladimir Putin, who is continuing his more than three-year military invasion of Ukraine.

“In recent days, Putin has shown his true face — mounting the biggest attack since the invasion began, with yet more bloodshed, yet more innocents killed and unprecedented violations of NATO airspace,” Mr. Starmer said. “These are not the actions of someone who wants peace.”

Mr. Trump called the dim prospects of ending the Russia-Ukraine war his “biggest disappointment.”

The American and British leaders are working together as a bit of an odd couple.

Mr. Trump leads the conservative MAGA movement, while Mr. Starmer leads the center-left Labor Party.

Both men condemned Palestinian militants in Hamas as an impediment to peace in Israel, though Mr. Starmer stressed the need for a Palestinian state alongside a safe and secure Israel.

Closer to home, Mr. Trump recently designated antifa, a decentralized left-wing movement, as a major terrorist organization. Mr. Starmer declined to say whether he wants to follow suit. He said Britain would make its own decisions.

The assassination of conservative activist Charlie Kirk last week loomed over Mr. Trump’s visit.

The president slammed late-night talk show host Jimmy Kimmel for saying “horrible things” about Mr. Kirk and brushed off claims that ABC’s indefinite suspension of Mr. Kimmel is an attack on free speech.

Mr. Trump said Mr. Kimmel was pulled off the air because no one was watching his show.

“He had very bad ratings, and they should have fired him a long time ago,” Mr. Trump said. “So you can call that free speech or not, he was fired for lack of talent.”

Mr. Starmer rejected claims that his government was suppressing online speech. He said he draws the line at discourse that promotes suicide among youths or encourages pedophilia.

The leaders seemed to find the most common ground on matters of dollars and cents.

Mr. Trump said he was “thrilled” that his first major trade deal this year was with Britain.

Some countries took a wait-and-see approach to Mr. Trump’s tariffs or dragged out talks, but Britain struck an early deal-in-principle to allow U.S. goods into its markets in exchange for tariff relief and aerospace transactions.

“I look forward to finalizing it very soon. We’ll have it done very quickly,” Mr. Trump said.

British goods still face Mr. Trump’s blanket 10% levy when they enter the U.S.

Yet the deal is expected to lower sector-specific tariffs and a fixed number of British vehicle exports.

Britain wants to reduce Mr. Trump’s 25% tariffs on steel and aluminum imports and hopes to slash them to zero. Details are being worked out.

“He’s a tough negotiator. I think it was a better deal for you than us,” Mr. Trump said of Mr. Starmer.

“It was a very good deal for both of us,” the British prime minister said.

The U.S.-British technology alliance will focus on developing new drugs, improving cancer care and producing lifesaving treatments, said a statement from the British government.

It will include investments in nuclear technology, clean energy, artificial intelligence and quantum computing.

Mr. Trump called the deal “the next logical step,” and Mr. Starmer hailed it as “a win for both sides.”

“The deals and announcements you’re announcing today break all records,” Mr. Starmer told the crowd at a reception that included several top business executives.

Mr. Starmer hopes the deal will be a lifeline for his political future, which has been thrown into doubt by a struggling economy plagued by massive debt, a high cost of living and low productivity.

Economic growth in Britain flatlined in July, according to data published last week by the British Office for National Statistics. Production output contracted by 0.9% in July after a 0.4% drop in June.

Mr. Starmer is betting the agreement will revive Britain’s reputation as a destination for overseas investment and technological innovation. The U.S. is Britain’s single largest trading partner, and several American tech companies have already invested billions of dollars in Britain.

As part of the deal, a northeast portion of Britain will be designated an AI “growth zone” and receive special support in planning and energy provision for hosting AI infrastructure such as data centers.

The British government says the plan could create more than 5,000 jobs and bring billions of dollars in investment.

Standing beside Mr. Trump at Chequers, Mr. Starmer said the U.S. and Britain renewed their “special relationship” for a new era.

“With a new agreement that we just signed this afternoon, we’re confirming our status as the first partners in science and technology, ready to define this century together,” he said. “Just as we did the last.”

• Tom Howell Jr. can be reached at thowell@washingtontimes.com.

• Jeff Mordock can be reached at jmordock@washingtontimes.com.

• Kerry Picket can be reached at kpicket@washingtontimes.com.