President Joe Biden congratulated fighter pilots for taking down the balloon in US airspace and above US territorial waters, after it spent days flying over the country.

"They successfully took it down. And I want to compliment our aviators who did it," Biden told reporters in Maryland.

US Secretary of Defense Lloyd Austin called the operation a "deliberate and lawful action" that came in response to "the PRC's unacceptable violation of our sovereignty," he said referring to China's official name, the People's Republic of China.

The action took place Saturday afternoon after three southeastern airports were temporarily shut down over what the Federal Aviation Administration called a "national security effort."

In footage shown on US television networks, the balloon appeared to be falling down vertically.

US officials were initially reluctant to shoot down the device, fearing it could hurt people and damage property on the ground.

But asked about the incident earlier Saturday, Biden promised "to take care" of it.

The controversy erupted Thursday, when American officials said they were tracking a large Chinese "surveillance balloon" in US skies.

That led Secretary of State Antony Blinken on Friday to scrap a rare trip to Beijing.

After initial hesitation, Beijing admitted ownership of the "airship," but said it was a weather balloon that had been blown off course, adding that it regretted the situation.

"The airship is from China. It is a civilian airship used for research, mainly meteorological, purposes," China's foreign ministry said in a statement Friday.

"The Chinese side regrets the unintended entry of the airship into US airspace due to force majeure," it said, using the legal term for an act outside of human control.

The balloon had flown over parts of the northwestern United States, including the state of Montana, that are home to sensitive airbases and strategic nuclear missiles in underground silos, adding to concerns.

US media reported early Saturday that the balloon was spotted over both North and South Carolina.

A sheriff in York County, South Carolina, warned locals not to try to shoot the craft down.

"Yes, there are reports that the Chinese balloon is flying over our area at the moment," said a post on the Twitter account of Sheriff Kevin Tolson.

"It's flying at 60,000+ feet. Don't try to shoot it!! Your rifle rounds WILL NOT reach it. Be responsible. What goes up will come down, including your bullets."

The balloon was reportedly flying at an altitude well above levels used by commercial airliners, though some private pilots said on social media that it was uncomfortably close.

Another suspected Chinese spy balloon was seen over Latin America, the Pentagon said Friday, without providing specifics as to its location.