(Makes clear in first paragraph that balloon tracked flying across the United States; adds that Blinken visit would have been first since 2017)
By Steve Holland, Idrees Ali and Humeyra Pamuk
WASHINGTON/BEIJING, Feb 3 (Reuters) - U.S. Secretary of State Antony Blinken has postponed a visit to China that had been expected to start on Friday after a Chinese spy balloon was tracked flying across the United States, a U.S. official said.
ABC News cited an U.S. official as saying Blinken did not want to blow the situation out of proportion by canceling his visit, but also did not want the balloon incident to dominate his meetings with Chinese officials.
A U.S. official confirmed the postponement to Reuters.
China earlier expressed regret that what it called a "civilian" airship had strayed into U.S. territory after being blown off course, an incident that sparked a political furor in the United States.
Pentagon spokesperson Air Force Brigadier General Patrick Ryder told reporters on Thursday that the government was tracking a high-altitude surveillance balloon over the continental United States and said it was "traveling at an altitude well above commercial air traffic and does not present a military or physical threat to people on the ground."
U.S. military leaders considered shooting down the balloon over Montana on Wednesday but eventually President Joe Biden decided against it because of the safety risk from debris, U.S. officials said on Thursday.
Republican Senator Tom Cotton had called for Blinken to cancel his trip, while Republican former President Donald Trump, a declared presidential candidate for 2024, posted "SHOOT DOWN THE BALLOON!" on his Truth Social media platform.
In a statement on Friday, China's foreign ministry said the balloon was for civilian meteorological and other scientific purposes and that it regretted that the airship had strayed into U.S. airspace.
It said it would continue to communicate with the United States to "properly handle" the unexpected situation. A Chinese government spokesperson said earlier that "China has no intention of violating the land territory and airspace of any sovereign country."
U.S. officials said they raised the matter with their Chinese counterparts through diplomatic channels. "We have communicated to them the seriousness with which we take this issue," a U.S. official said.
The postponement of Blinken's trip, which was agreed to in November by Biden and Chinese President Xi Jinping, will be a blow to those on both sides who saw it as an overdue opportunity to stabilize an increasingly fractious relationship. The last visit by a U.S. secretary of state was in 2017.
China is keen for a stable U.S. relationship so it can focus on its economy, battered by the now-abandoned zero-COVID policy and neglected by foreign investors alarmed by what they see as a return of state intervention in the market.
In recent months Chinese leader Xi Jinping has met with world leaders, seeking to re-establish ties and settle disagreements.
Relations between China and the United States have soured in recent years, particularly following then-U.S. House Speaker Nancy Pelosi's visit to Taiwan in August, which prompted dramatic Chinese military drills near the self-ruled island.
Since then, Washington and Beijing have sought to communicate more frequently and prevent ties from worsening.
One U.S. official said the balloon was assessed to have "limited additive value from an intelligence collection perspective."
The United States took "custody" of the balloon when it entered U.S. airspace and had observed it with piloted U.S. military aircraft, one U.S. official said.
One American official said the flight path would carry the balloon over a number of sensitive sites, but did not give details. Malmstrom Air Force Base in Montana is home to 150 intercontinental ballistic missile silos.
The news initially broke on Thursday as CIA Director William Burns was speaking at an event at Washington’s Georgetown University, where he called China the "biggest geopolitical challenge" facing the United States.
U.S. Senator Marco Rubio, the top Republican on the Senate intelligence committee, said the spy balloon was alarming but not surprising.
"The level of espionage aimed at our country by Beijing has grown dramatically more intense & brazen over the last 5 years," Rubio said on Twitter.
The Billings, Montana, airport issued a ground stop as the military mobilized assets including F-22 fighter jets in case Biden ordered that the balloon be shot down.
Defense expert John Parachini estimated the size of the balloon was equivalent to three bus lengths.
Billings resident Chase Doak, who filmed it on Wednesday, said at first he thought it was a star.
"But I thought that was kind of crazy because it was broad daylight and when I looked at it, it was just too big to be a star," he told Reuters.
Such balloons typically operate at 80,000-120,000 feet (24,000-37,000 meters), well above where commercial air traffic flies. The highest-performing fighter aircraft typically do not operate above 65,000 feet, although spy planes such as the U-2 have a service ceiling of 80,000 feet or more.
Craig Singleton, a China expert with the Foundation for Defense of Democracies, said that such balloons had been widely used by the United States and Soviet Union during the Cold War and are a low-cost intelligence gathering method. (Reporting by Steve Holland, Idrees Ali, Humeyra Pamuk, Phil Stewart, Michael Martina and David Brunnstrom in Washington; additional reporting by Tony Munroe, Ryan Woo and Yew Lun Tian in Beijing, Akriti Sharma in Bengaluru, Greg Torode in Hong Kong, and Lion Schellerer in Singapore; Editing by Don Durfee and Jonathan Oatis)