WASHINGTON >> U.S. intelligence agencies have assessed that China’s spy balloon program is part of a global surveillance effort that is designed to collect information on the military capabilities of countries around the world, according to three American officials.

The balloon flights, some officials believe, are part of an effort by China to hone its ability to gather data about U.S. military bases — in which it is most interested — as well as those of other nations in the event of a conflict or rising tensions. U.S. officials said this week that the balloon program has operated out of multiple locations in China.

At a news conference Wednesday, Brig Gen. Patrick S. Ryder, the Pentagon spokesperson, said that over the past several years Chinese balloons have been spotted operating over Latin America, South America, Southeast Asia, East Asia and Europe.

“This is what we assess as part of a larger Chinese surveillance balloon program,” Ryder said.

Antony J. Blinken, the U.S. secretary of state, said at another news conference in Washington that the State Department has shared information on the spy balloon program with dozens of countries, both in meetings in Washington and through U.S. embassies abroad.

“We’re doing so because the United States was not the only target of this broader program, which has violated the sovereignty of countries across five continents,” he said.

Biden administration officials said over the weekend that the balloon that crossed the United States last week was part of a larger Chinese surveillance effort. The Washington Post reported Tuesday new details about China’s balloon surveillance program, including that the program had operated partly out of the islands of Hainan province off China’s south coast.

The balloons have some advantages over the satellites that orbit the Earth in regular patterns, U.S. officials say. They fly closer to Earth and drift with wind patterns, which are not as predictable to militaries and intelligence agencies as the fixed orbits of satellites, and they can evade radar. They can also hover over areas while satellites are generally in constant motion. Simple cameras on balloons can produce clearer images than those on orbital satellites, and other surveillance equipment can pick up signals that do not reach the altitude of satellites.

American officials, who spoke on the condition of anonymity to discuss sensitive matters, said that intelligence agencies during the Biden administration had developed a far deeper understanding of the scope and size of the Chinese spy balloon effort, discovering earlier incursions that had been classified as unknown events and tracking new operations by the Chinese spy balloons.

However, U.S. officials said most of the previous observations of the surveillance balloons had been short. The latest spy balloon’s transit across the United States gave the U.S. military and intelligence agencies a long period of time to study the capabilities of the surveillance equipment attached to it. Officials said their knowledge of what China was capable of collecting from their balloon program has increased dramatically.

“This last week provided the United States with a unique opportunity to learn a lot more about the Chinese surveillance balloon program, all information that will help us to continue to strengthen our ability to track these kinds of objects,” Ryder said.

Before last week, the United States had tracked Chinese surveillance balloons collecting information from more than a dozen countries around the world, officials said. Some of the Chinese efforts appeared to be focused on the Pacific region, and a number of the balloons and other Chinese surveillance efforts have been detected over U.S. allies and partners in that region.

The New York Times reported Saturday that a classified intelligence report given to Congress last month highlighted at least two instances of a foreign power using advanced technology for aerial surveillance over U.S. military bases: one inside the continental United States and the other overseas. The research suggested China was the foreign power, U.S. officials said. The report also discussed surveillance balloons.

In the United States, at least five spy balloons have been observed — three during the Trump administration and two during the Biden administration. The spy balloons observed during the Trump administration were initially classified as unidentified aerial phenomena, U.S. officials said. It was not until after 2020 that officials closely examined the balloon incidents under a broader review of aerial phenomena and determined that the incidents were part of the Chinese global balloon surveillance effort.

While assessments differ on what the Chinese surveillance balloons can collect, many officials believe Chinese satellites are generally as capable of image collection as a balloon. But the balloons can linger longer over a site and potentially collect multiple forms of intelligence, although officials have not described what they know about the balloons’ collection ability.

The Chinese government has claimed the balloon was meant to collect weather information. Ryder said that if the balloon that traveled across the United States were really for civilian purposes, Beijing would have given Washington advanced warning.

“The PRC did not do that,” Ryder said, referring to the People’s Republic of China. “They didn’t respond until after they were called out. We’ll just leave it at that.”

The new State Department campaign to divulge details of China’s spy balloon program to other governments is aimed at making allies and partners aware of the extent of Chinese aerial espionage efforts so that they can push back on Beijing’s efforts, U.S. officials said. Wendy Sherman, the deputy secretary of state, briefed U.S. diplomats abroad on the balloon program in a video conference Monday and is preparing to speak publicly to the Senate Foreign Relations Committee on Thursday, officials said.

U.S. diplomats abroad have been setting up meetings in their host countries to inform governments of the surveillance program.

The U.S. briefings to foreign officials are designed to show that the balloons are equipped for intelligence gathering and that the Chinese military has been carrying out this collection for years, targeting, among other sites, the territories of Japan, Taiwan, India and the Philippines. U.S. diplomats argue China has violated the sovereign airspace of numerous countries, even as Chinese officials continue to insist that the two balloons seen last week over the United States and Latin America were civilian-mission machines.

“China has taken a ham-fisted approach to public information management,” said Jude Blanchette, a China scholar at the Center for Strategic and International Studies in Washington. “The moment they issued the statement of regret, they should have stopped there. Their lies that this was a civilian weather balloon made things worse.”

The Chinese Foreign Ministry made the weather balloon claim in a statement Friday, the day after the Pentagon announced a Chinese spy balloon was hovering over Montana, in an apparent attempt to persuade Blinken not to cancel a weekend trip he had planned to make to Beijing. Planning for the trip began after President Joe Biden met with President Xi Jinping of China in Bali, Indonesia, in November, and Blinken had been expected to hold talks with Xi.

But soon after China released its statement, Blinken called Wang Yi, the Chinese Communist Party’s top foreign policy official, to tell him that China had committed “an irresponsible act” and that the trip was off.

On Wednesday, Blinken discussed China’s aggressive military actions with Jens Stoltenberg, secretary-general of the North Atlantic Treaty Organization, during a meeting in Washington. At their joint news conference in the afternoon, Stoltenberg listed strategic problems with China, including its belligerence over Taiwan and its partnership with Russia. “NATO allies have real concerns,” he said.

When asked by a reporter about the U.S. government’s assertion that China had sent one or more spy balloons over Europe, Stoltenberg hinted at such an episode but did not explicitly confirm it. He spoke about China using a range of intelligence-gathering methods in Europe.

“The Chinese balloon over the United States confirms a pattern of Chinese behavior, where we see China over the last years has invested heavily in new military capabilities, including different types of surveillance and intelligence platforms,” he said.

“And we’ve also seen increased Chinese intelligence activities in Europe — again, different platforms,” Stoltenberg added. “They use satellites, they use cyber, and, as we’ve seen over the United States, also balloons.”

This article originally appeared in The New York Times.