The suspected Chinese surveillance balloon that drifted across American airspace over past days and was shot down by the US Air Force over the Atlantic on the weekend triggered a diplomatic maelstrom and blew up on social media.
China insists the massive white orb was just an errant civilian airship used mainly for meteorological research that went off course due to winds and had only limited "self-steering" capabilities.
It also issued a threat of "further actions."
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In a statement after the craft was shot down, China's Ministry of Foreign Affairs said the use of force by the US was "an obvious overreaction" and a serious violation of international practice.
It added: "China will resolutely uphold the relevant company's legitimate rights and interests, and at the same time reserving the right to take further actions in response."
The US says it was a Chinese spy balloon without a doubt.
Its presence prompted Secretary of State Antony Blinken to cancel a weekend trip to China that was aimed at dialling down tensions that were already high between the countries.
The Pentagon says the balloon, which was carrying sensors and surveillance equipment, was maneuverable and showed it could change course.
It loitered over sensitive areas of Montana where nuclear warheads are siloed, leading the military to take actions to prevent it from collecting intelligence.
A US Air Force fighter jet shot down the balloon on Saturday off the Carolina coast by deploying a Sidewinder air-to-air missile.
Television footage showed a small explosion, followed by the balloon slowly drifting toward the water.
An operation is underway to recover the remnants.
But questions linger over the incident. Here is what we know and don't know.
It's a bird, it's a plane, it's a spy balloon
The Pentagon and other US officials said it was a Chinese spy balloon — about the size of three school buses — that moved east over America at an altitude of about 18,600m.
The US says it was being used for surveillance and intelligence collection, but officials have provided few details.
Former FBI counter-terrorism expert Peter Strzok told Today the balloon was a large sophisticated structure and was probably capable of gathering detailed intelligence.
Was the balloon armed?
In the first public US statement, Brigadier General Pat Ryder, the Pentagon press secretary, said that the balloon was not a military or physical threat — an acknowledgement that it was not carrying weapons.
But other experts are worried the craft could easily be fitted with weapons to destroy or damage targets below it.
Anthony Shaffer, who served as senior intelligence officer in the US army, told Today he was concerned the balloons could become "weaponised".
He pointed to how the Japanese fitted explosive devices to high-altitude balloons during World War II and flew them over the north-western US.
"This is something we need to be worried about," he said.
"(The question) is, potentially, what do they put below that balloon that could be potentially weaponised?"
What about the balloon wreckage?
Once the balloon crashed into the water, US officials said, the debris field stretched at least 14km, and was in water 15m deep.
That depth is shallower than what they had planned, making it easier to retrieve pieces of the sensor package and other parts that may be salvageable.
Officials said the USS Oscar Austin, a Navy destroyer, the USS Carter Hall, a dock landing ship, and the USS Philippine Sea, a guided missile cruiser, are all part of the recovery effort, and a salvage vessel will arrive in a few days.
They said navy divers will be on hand if needed, along with unmanned vessels that can recover debris and lift it back up to the ships.
The FBI will also be present to categorise and assess anything recovered, officials said.
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Are there other Chinese balloons in the sky?
The Pentagon acknowledged reports of a second balloon flying over Latin America.
"We now assess it is another Chinese surveillance balloon," Ryder said.
Officials said the balloons are part of a fleet that China uses for surveillance, and they can be manoeuvred remotely through small motors and propellers.
Colombian media reported sightings of a balloon flying at about 20,000m over the South American country's airspace, citing the Colombian military.
There have also been reports that there was a balloon seen flying over Costa Rica, which could be the same one as seen in Colombia.
Shaffer pointed to remarks by US Senator Marco Rubio who claimed a similar Chinese balloon had been seen over Hawaii, a key Pacific naval base.
