US Navy divers are working to recover the wreckage of the Chinese surveillance balloon that was shot down off the coast of South Carolina.
Fighter jets brought the craft down over US territorial waters on Saturday and debris is spread over a wide area.
The US believes the balloon was monitoring sensitive military sites.
Its discovery set off a diplomatic crisis, with US Secretary of State Antony Blinken immediately calling off this weekend’s trip to China.
The Chinese authorities denied it was used for spying and insisted it was a weather ship blown astray.
Admiral Mike Mullen, former chair of the US Joint Chiefs of Staff, said on Sunday he thought the Chinese military might have launched the balloon intentionally to disrupt Mr Blinken’s trip to China. His visit would have been the first such high level US-China meeting there in years.
Adm Mullen rejected China’s suggestion it might have blown off course, saying it was manoeuvrable because “it has propellers on it”.
“This was not an accident. This was deliberate. It was intelligence,” he added.
Republican politicians. meanwhile, accused US President Joe Biden of a dereliction of duty for allowing the balloon to traverse the country unhindered.
Marco Rubio, vice-chair of the Senate intelligence committee, told CNN it was a “brazen effort” by China to embarrass the president ahead of his State of the Union address on Tuesday.
The high-altitude balloon – thought to be the size of three buses – was shot out of the sky by a Sidewinder air-to-air missile fired from an F-22 jet fighter. It came down about six nautical miles off the US coast at 14:39 EST (19:39 GMT) on Saturday.
US TV networks broadcast the moment the missile struck, with the giant white object falling to the sea after a small explosion.
Police have warned people in the area not to touch or move any debris they find. “Tampering could interfere in [the] investigation,” Horry County Police Department said.
The remnants of the object landed in 47ft (14m) of water – shallower than officials expected – and is spread over seven miles (11km).
Explaining the decision to shoot the balloon down, a US defence official said in a statement, that “while we took all necessary steps to protect against the PRC [China] surveillance balloon’s collection of sensitive information, the surveillance balloon’s overflight of US territory was of intelligence value to us”.
China’s foreign ministry expressed “strong dissatisfaction and protest against the US’s use of force to attack civilian unmanned aircraft”. In a written statement, the Chinese government said it would “resolutely safeguard” the rights and interests of the company operating the balloon and that it reserved the right to “make further responses if necessary”.
Mr Biden first approved the plan to bring down the balloon on Wednesday, but decided to wait until the object was over water so as not to put people on the ground at risk.
The US Federal Aviation Administration (FAA) briefly paused all civilian flights at three airports around the South Carolina coast and advised mariners to leave the area.
Relations between China and the US have been strained by the incident, with the Pentagon calling it an “unacceptable violation” of its sovereignty.
US military officials on Friday said a second Chinese spy balloon had been spotted over Latin America. The same day, Colombia’s Air Force said an identified object – believed to be a balloon – was detected on 3 February in the country’s airspace at above 55,000ft.