As signs emerged that President Biden was gearing up to stop the Japanese steel maker Nippon Steel from acquiring Pittsburgh-based U.S. Steel, top Japanese officials repeatedly warned that quashing the merger would hinder economic ties between the allies.

Japan’s biggest business lobby, Keidanren, said in September that America’s investability would be tarnished if Nippon Steel’s $15 billion bid was blocked. Prime Minister Shigeru Ishiba of Japan reached out to Mr. Biden asking him to approve the deal during what he called a critical juncture.

In the United States, during a heated presidential campaign, both Mr. Biden and his opponent, Donald J. Trump, came out against the Japanese acquisition of U.S. Steel, an iconic American company in a key electoral state. Mr. Biden on Friday stopped the merger from going forward, arguing that foreign control of U.S. Steel would jeopardize America’s national security.

Nippon Steel and U.S. Steel assailed Mr. Biden’s decision, calling the deal’s review “deeply corrupted by politics” and its rejection “shocking.” The companies said on Friday they would consider taking legal action to try to revive the deal.

But while Mr. Biden’s decision sends a worrying sign to Japanese leaders about the perils of American politics, it is not expected to stop other companies from seeking to do deals in the United States.

Japanese businesses have had little choice but to move significantly toward the United States in recent years, as they have had a harder time investing in China. Now, in anticipation of a second Trump administration, executives are even more busily lining up fresh investments in America.

For decades, Japanese companies have sought growth opportunities outside the country, where the population is aging and declining, and currency fluctuations have imperiled export activities. Much of that expansion has been aimed at the United States and China, which have long vied to be Japan’s biggest trade partner.

But it has gotten more difficult for Japanese firms to operate in China because of less-friendly regulations and competition from state-backed rivals. China’s share of Japanese foreign direct investment has declined steadily over the past half-decade, while it has climbed in the United States. Japan became the top investor in America in 2019 — a position it has maintained each year since.

While the volume of Japanese-led deals in the United States stalled slightly last year, trade experts expect investments to pick up again when President-elect Trump takes office. That is because the risk of increased tariffs gives Japanese and other foreign companies a greater incentive to invest and produce in the United States over other countries, especially China.

Japanese power companies are eyeing a number of potential investments in natural gas and other energy projects promoted by Mr. Trump. At a Trump news conference last month, Masayoshi Son, the chief executive of the Japanese technology company SoftBank, pledged to invest $100 billion in the United States over the next four years.

“Business leaders will not look at a unique case like Nippon Steel and make decisions to withhold investment in the United States,” said Masahiko Hosokawa, a professor at Meisei University and former senior official at Japan’s trade ministry. “This is not a case that will cause damage, especially in the mid- to long term.”

Japan’s biggest business publication, Nikkei, wrote on Saturday that Nippon Steel’s crushed bid was a result of a mistaken calculation that “economic rationality” would prevail even in a presidential election year.

In December 2023, when Nippon Steel announced its plans to acquire U.S. Steel, executives at the company thought the deal would proceed quickly. As the Committee on Foreign Investment in the United States reviewed the deal, Nippon Steel doubled down on its bet on the United States, withdrawing from a longstanding joint venture in China that might have elicited suspicion from regulators.

Nippon Steel’s bid instead drew intense backlash from some politicians and union leaders, who said the purchase of a storied American manufacturer by a foreign entity would undermine national security and local industry. Early on, both President Biden and President-elect Trump said they were against the deal.

As part of its bid, Nippon Steel offered a large premium on U.S. Steel shares and promised to invest billions in the American company’s plants. Takahiro Mori, the Nippon Steel executive in charge of the deal, traveled repeatedly to the United States to hold meetings with over 1,000 employees, local officials and others with a stake in the deal.

Late last month, the review committee, known as CFIUS, sent a letter to the White House saying it was unable to decide whether Nippon Steel should be allowed to buy U.S. Steel. That paved the way for President Biden to terminate the transaction.

China, at the same time, has been trying to bolster relations with Japan. Some speculate the moves were made in anticipation of a trade war between the United States and China that is expected to worsen when Mr. Trump takes office.

In November, Beijing restarted a policy allowing Japanese nationals to make short-term visits without visas. Japan has been working to ease visa requirements for Chinese visitors. In September, China said it would gradually resume Japanese imports of seafood after banning them in response to Japan’s release of treated radioactive water into the ocean.

William Chou, the deputy director of the Japan policy center at the Hudson Institute, a Washington think tank, said he viewed the Nippon Steel case as a “one-off.”

“The U.S. has a long history of being a stable environment, and China is not an attractive place to increase investments at the moment,” Mr. Chou said. “But that’s not to say Japan won’t feel the inclination to hedge its bets.”

In July, as signs emerged that Nippon Steel’s acquisition might not be approved, one of its distributors, Marubeni-Itochu Steel, said it would purchase a stake in a Spanish steel company.

A person with knowledge of the purchase said Nippon Steel was eager for Marubeni-Itochu Steel to expand its presence in Europe, an increasingly important market since hopes were fading that Nippon Steel would gain a bigger toehold in the United States.

Andrew here. Happy New Year and happy Saturday. This morning, we’re taking a look at what may — or may not — happen in 2025. This is not an effort to crystal-ball the future so much as it is a rundown of big topics that the DealBook team and I have on our radar screen in the new year.

On this list: Changes to deal-making in the new Trump era, the future (or end) of D.E.I. efforts, the growing momentum of workers returning to the office, the evolving relationship between China and the U.S., new investments in artificial intelligence, and yes, the role of Elon Musk in all of the above. Let us know what you think. And we’ll revisit this list at the end of the year.

Deals will flow. Deal makers pretty much universally expect a flood of deals under President-elect Donald Trump after four years of pent-up activity under President Biden, whose antitrust enforcers challenged a record number of mergers. The more interesting question: Which kinds of companies will make those deals? More M.&A. in the energy sector seems probable, given Trump’s support for the industry. Bank deals could also take off: After the regional banking crisis, Treasury Secretary Janet Yellen said the country could benefit from more mergers. Deals may also pop up to address cybersecurity concerns, the impact of GLP-1 drugs and the fierce A.I race.

Media companies will reshuffle. Media executives and their advisers have been saying for years that the industry needs a drastic overhaul to address its new reality: an overabundance of streaming options and the decline of the legacy cable industry. Deals that were effectively considered a no-go under Biden’s aggressive antitrust enforcers may finally be given a green light under a Trump administration.

Everyone is watching to see what a handful of key players do next: Will Comcast’s move to spin off its cable business inspire others, such as Warner Bros. Discovery, to do the same? Will Paramount use Larry Ellison’s deep pockets to acquire streaming businesses? Will Rupert Murdoch respond to his failed attempt to change his family trust by selling Fox, making it bigger, or trying to buy out some of his children? Will Trump allow a major media company (or his own) to buy TikTok?

Big Tech may not catch a break. While corporate America has been anticipating a longer leash under the Trump administration, Silicon Valley giants may still face a lot of scrutiny. Several of Trump’s picks to lead key regulators — Andrew Ferguson at the Federal Trade Commission, Gail Slater at the Justice Department’s antitrust division and Brendan Carr of the Federal Communications Commission — are expected to keep looking closely at Big Tech.

Unlike Lina Khan, the outgoing F.T.C. chief whose lawsuits fighting tech giants’ market power came from a progressive perspective, many of Trump’s picks have accused companies like Google and Meta of silencing conservative voices.

What will Elon Musk do with his power? The tech billionaire has been one of the most influential and omnipresent voices in Trump’s ear since the election, and his perch as co-head of the Department of Government Efficiency potentially gives him great sway — some critics say too much — over government agencies that fear budget cuts.

But the extent of Musk’s agenda remains unclear. He has already fought longtime Trump allies in defense of the skilled-worker visa program known as H-1B, a battle that he appears to have won for now. He’s also likely to push for further deregulation and more openness when it comes to A.I. and crypto. One unknown: how Musk, who sells a lot of Teslas in China, will weigh in on Beijing policy.

Executives want employees back in the office — and politics out of it. Starting this month, many of Amazon’s corporate staff members were required to work from the office five days a week, up from three days a week previously. The tech company’s return-to-office mandate caused waves and there are signs that office attendance across industries is ticking up.

But remote work remains prevalent, with about 30 million workers in hybrid or fully remote arrangements. Will other big tech companies follow Amazon’s lead in 2025?

Along with office attendance, executives are increasingly cracking down on employee activism. Starbucks sued a union that represents some of its workers after local affiliates posted pro-Palestinian social media posts (the union sued back). After Google fired dozens of employees last year over protests related to the company’s cloud computing contract with the Israeli government, the Google C.E.O., Sundar Pichai, told employees that work was not a place to “fight over disruptive issues or debate politics.” The sentiment seems to be catching on: Big tech companies that saw protests after Trump was elected in 2016 were silent after he was elected in 2024. Will the quiet continue?

D.E.I. will fight for its life. In 2024, the programs were attacked by lawsuits, activists such as Robby Starbuck and conservative lawmakers. As companies prepare for a Trump administration, some, like JetBlue and Molson Coors, have flagged diversity, equity and inclusion policies as a risk factor in their security filings. Walmart, Ford Motor and Toyota have rolled back some programs, and others are rebranding their efforts without advertising it, in hopes of attracting less attention. Fewer have publicly fought back, though Costco last month challenged a proposal by activist shareholders looking to end its D.E.I. efforts.

Infrastructure will become a growing focus of the A.I. race. The fight to dominate artificial intelligence is also spurring investment in infrastructure to generate the huge amount of electricity it requires. The International Energy Agency has forecast data center energy demand could double by 2026.

Some of the tech industry’s highest-profile executives are investing. Sam Altman of OpenAI, Jeff Bezos and Bill Gates are all backing nuclear fusion start-ups. Microsoft and BlackRock launched a $30 billion fund to invest in A.I. infrastructure last year. Silver Lake, the private equity firm, is spending big on data centers.

One name to watch this year: SoftBank. The Japanese tech investor has reportedly talked to Apollo, the private equity firm, about creating a $20 billion A.I. investment fund, and Masa Son, SoftBank’s mercurial C.E.O., is hunting for deals.

Defense tech could be in for a bumper year. Trump has promised to end the war in Ukraine. Whether or not he succeeds, the defense tech industry will benefit either way. It’s already happening: Venture investment in defense start-ups soared last year, and by September had surpassed the total amount invested in 2023. Palantir, a data analytics company, was a star performer. Its market capitalization jumped almost fivefold to $180 billion in 2024, its operating margins have risen sharply and it joined the S&P 500 in September.

Others are also profiting from rising global uncertainty. Anduril Industries, a California-based defense start-up backed by Peter Thiel, the venture capitalist and Palantir co-founder, announced in August that it had raised $1.5 billion in a funding round that valued it at $14 billion. And Helsing, a German start-up that uses A.I. to process live data from the battlefield, is one of Europe’s best-funded companies.

If Trump does manage to end the war, it’s plausible that Western defense companies will find opportunities helping to build Ukraine’s military capability. If he doesn’t, more of their tech may be deployed on the ground there. Smaller, A.I.-powered companies are already testing their equipment in real time in a war where drones and other tech are playing a big role.

How will Trump take on China, and how will Beijing respond? Trump has promised to increase tariffs on goods from China, accusing Beijing and its companies of unfair competition among other things. It’s the same stance he took during his first presidency, when he ratcheted up trade restrictions with the world’s second-biggest economy.

Much uncertainty remains about how Trump’s threats will play out once he’s in office, but Chinese companies have proven adept at finding ways around previous restrictions. Some moved final manufacturing and assembly operations to countries like Mexico, Vietnam and Malaysia so they could export directly to the United States without paying the 25 percent levy Trump imposed during his first term. Other businesses, such as Temu, the e-commerce company, set up operations in the U.S. to appear less Chinese and more American. Even after that facade faded, it’s still thriving: Temu was the most downloaded free app in Apple’s App Store in 2024.

How will Trump’s policies affect the economy? Trump’s plan to cut taxes and red tape is expected to keep G.D.P. growth steady at about 3 percent this year, and bolster American businesses’ bottom line in the short run. But his vow to impose tariffs on some of the country’s biggest trading partners on his first day in office could seriously crimp global growth in 2025.

Another pressing question is whether Trump will dismantle the Inflation Reduction Act, which would put billions of dollars’ worth of tax credits in jeopardy. That prospect has prompted even some Big Oil executives to lobby Trump hard to preserve the law.

A wild-card: inflation. Will Trump’s policies reignite it, spooking both the Fed and the so-called bond vigilantes? Keep an eye on the yield for 10-year Treasury notes, market watchers say. A spike there could force the administration to dial back its most ambitious plans to stimulate growth. Already, inflation fears have prompted the Fed to slash its forecast for 2025 rate cuts.

Thanks for reading! We’ll see you Monday.

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