The Treasury Department imposed sanctions on a Beijing-based cybersecurity company on Friday, blaming it for helping Chinese hackers infiltrate U.S. communications systems and conduct surveillance across four continents.

In an announcement, the department said the company, Integrity Technology Group, had supported a Chinese state-sponsored hacking group known as Flax Typhoon in a campaign to break into foreign networks between the summer of 2022 and 2023, saying it found the group had “routinely sent and received information from Integrity Tech infrastructure.”

The action came after the Treasury Department revealed in a letter to lawmakers this week that a Chinese intelligence agency had breached its systems in what appeared to be an espionage operation, gaining access to the workstations of government employees and unclassified documents.

A spokesman for the department did not specify whether Flax Typhoon had been implicated in the attack on the Treasury Department’s systems, or whether the sanctions were merely part of a larger operation to disrupt China’s cybercapabilities.

The sanctions also follow the much more damaging revelation last year that a group linked to Chinese intelligence agencies and known as Salt Typhoon had hacked U.S. telecommunications networks, targeting the telephone conversations and text messages of an array of top political figures, including President-elect Donald J. Trump.

Like Salt Typhoon, Flax Typhoon is among a handful of groups that Microsoft has publicly identified as being linked to Chinese intelligence and responsible for a range of state-sponsored cyberattacks. The group has been active since 2021 and appears focused on targets in Taiwan and the United States, according to the Congressional Research Service.

“The Treasury Department will not hesitate to hold malicious cyberactors and their enablers accountable for their actions,” Bradley T. Smith, an acting under secretary of the Treasury, said in a statement. “The United States will use all available tools to disrupt these threats as we continue working collaboratively to harden public and private sector cyberdefenses.”

In September, the F.B.I. said it had taken down a network of 200,000 consumer devices in the United States and abroad that had been compromised with malware and weaponized by Flax Typhoon.

The sanctions announced on Friday generally prohibit financial institutions and individuals from transacting with Integrity Technology Group, and freeze any of its assets in the United States.

It was not immediately clear what the breach of the Treasury Department may have achieved, but the agency represents an attractive target for state-sponsored hackers because of its Office of Foreign Assets Control, which is responsible for imposing sanctions and determining which individuals represent a threat to national security.

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.