The US says it has successfully concluded recovery efforts off South Carolina to collect sensors and other debris from a suspected Chinese surveillance balloon shot down by a fighter jet on February 4, and investigators are analysing its “guts”.

But US and Canadian authorities also announced they had called off searches for three unidentified objects shot down over last weekend, without finding any debris.

President Joe Biden said this week the US intelligence community believed the other three objects were most likely balloons tied to private companies, recreation or research institutions – not China’s spy program.

The last of the debris from the Chinese balloon, downed by a Sidewinder missile, is now being analysed, the US military’s Northern Command said.

Reuters was first to report the conclusion of the recovery efforts for the suspected Chinese spy balloon, which were halted on Thursday.

“It’s a significant amount (of recovered material), including the payload structure as well as some of the electronics and the optics, and all that’s now at the FBI laboratory in Quantico,” said National Security Council spokesperson John Kirby.

Intelligence windfall

Kirby said the United States had already learned a lot about the balloon by observing how it flew over the United States.

“We’re going to learn even more, we believe, by getting a look at the guts inside it and seeing how it worked and what it was capable of,” he told a White House news briefing.

The US military said Navy and Coast Guard vessels that had been scouring the sea for nearly two weeks have departed the area.

“Air and maritime safety perimeters have been lifted,” Northern Command said.

The US military has said it believes it has collected all the Chinese balloon’s priority sensors and electronics as well as large sections of its structure, elements that could help counterintelligence officials determine how Beijing may have been collecting and transmitting surveillance information.

The balloon, which Beijing denies was spying, spent a week flying over the US and Canada before being shot down on Biden’s orders off the Atlantic Coast.

The episode caused an uproar in Washington and led the US military to search the skies for other objects not being captured on radar.

Other searches called off

Northern Command carried out an unprecedented three shootdowns of unidentified “objects” between last Friday and Sunday.

Late on Friday, it said search operations for the two objects shot down in US airspace – one over Alaska and the other over Lake Huron – had concluded, having “discovered no debris”.

The third object was shot down over Canada’s Yukon. The Royal Canadian Mounted Police said it had also decided to end search efforts due to the snowfall that had occurred, decreasing the chances the object would be found.

The Chinese balloon incident prompted US Secretary of State Antony Blinken to postpone a planned visit this month to Beijing and has further strained relations between Washington and Beijing.

-AAP