The United States said Thursday it is tracking what it believes to be a Chinese high-altitude surveillance balloon that has flown for days over the country, but China acknowledged later that it is a weather observation airship that made an unintended entry into U.S. airspace.

Pat Ryder, press secretary of the U.S. Defense Department, said it is "currently traveling at an altitude well above commercial air traffic and does not present a military or physical threat to people on the ground."

A high altitude balloon floats over Billings, Mont., on Feb. 1, 2023. (Larry Mayer/Billings Gazette/AP/Kyodo)

The Chinese Foreign Ministry expressed regret in a statement Friday, saying the civilian airship used for meteorological research deviated far from the intended course due to westerlies and limited control capability.

"China will maintain communication with the United States to handle this unexpected situation properly," the ministry said.

Ryder added that similar activity has been detected at times over the past several years, while a senior defense official said the balloon entered the continental U.S. airspace a "couple of days ago."

The senior official, who declined to specify the size of the balloon and many other details, disclosed that one of the locations it had traveled was above some sparsely populated areas in the western state of Montana, which is home to one of the country's three nuclear missile silo fields.

The official said President Joe Biden asked for military options when being briefed on the discovery of the balloon, but the Pentagon eventually opted not to shoot it down because it is "large enough to cause damage" from falling debris.

"Clearly, the intent of this balloon is for surveillance, and so the current flight path does carry it over a number of sensitive sites," he said.

But the official, who spoke to reporters on condition of anonymity, said the United States has assessed it has "limited additive value from an intelligence collective collection perspective."

The official said the United States has already conveyed to China the "seriousness" of the issue through multiple channels.

Before her ministry acknowledged the Chinese balloon's presence in U.S. airspace, spokeswoman Mao Ning stressed at a press conference in Beijing on Friday that China has no intention of violating the territory and airspace of any sovereign country.

The Canadian Department of National Defense separately said Thursday that a high-altitude surveillance balloon was detected in a "potential second incident," and the country is taking steps to ensure the security of its airspace.

"Canada's intelligence agencies are working with American partners and continue to take all necessary measures to safeguard Canada's sensitive information from foreign intelligence threats," the department said in a statement.

The discovery comes as Secretary of State Antony Blinken is due to make his first trip to Beijing for follow-up talks after Biden, for the first time, held a face-to-face summit with Chinese President Xi Jinping in November.

During the meeting, held on the sidelines of a Group of 20 summit in Indonesia, the two presidents agreed to facilitate communication, despite very different positions on Taiwan, Russia's invasion of Ukraine, and economic and human rights issues between the world's two largest economies.

Blinken's visit to Beijing, the date of which has still not been officially announced, is likely to take place from Feb. 5 to 6. The trip will be the first by a U.S. secretary of state in more than four years.

Related coverage:

Blinken puts off China trip after spy balloon detected over U.S.

U.S. plane has near miss with China fighter over South China Sea