A suspected Chinese spy balloon that was shot down by the US over the weekend was 60m (200ft) tall – comparable to a 20-storey building.
Glen VanHerck, commander of North American Aerospace Defence Command (NORAD), told reporters that the balloon was also carrying a load similar in size to a commercial plane.
He added that it most likely weighed in the region of 71st (1,000lbs).
The balloon was shot down with a missile fired by an F-22 fighter aircraft, about six nautical miles off the coast near Myrtle Beach, South Carolina, Pentagon officials said on Sunday.
Television footage showed a small explosion, followed by the balloon descending toward the water.
The height of the balloon, twice the size of the Rockefeller Center Christmas tree – as well as the load – were factors in the “decision-making process” to wait and shoot the object down until it was over the Atlantic Ocean, NBC reported.
Pentagon officials said they feared debris could cause civilian injuries, death or damage to properties. Another concern was that the balloon may have been carrying explosives, Mr VanHerck added.
Security zone implemented in South Carolina waters
On Monday, the US coast guard imposed a temporary “security zone” in waters off the South Carolina coast, as a result of the military’s search and recovery of debris.
Officials hope to gain valuable intelligence on the balloon’s operations by retrieving as many components as possible, a White House spokesperson said.
China insisted the balloon was used for meteorological and other scientific research and had been blown off course.
In a statement on Sunday, the Chinese foreign ministry called the shooting an “obvious overreaction” that “seriously violated international conventions”.
It warned of “serious repercussions” while the White House said the balloon’s flight over the US had done nothing to improve already tense relations with China.
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China apologises for balloon over Costa Rica
During a statement, Chinese foreign ministry spokesperson Mao Ning said another balloon had been spotted over Latin America after “severely deviating” and becoming affected by weather.
According to a brief statement from Costa Rica’s foreign ministry, the Chinese embassy in San Jose “apologised for the incident”, while insisting the balloon was focused on scientific research.
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At the time planes were notified but no further action was taken, according to the civil aviation director.