The US has shot down a giant Chinese balloon that it says has been spying on key military sites across America.

The Department of Defense confirmed its fighter jets brought down the balloon over US territorial waters.

Three airports were shut and airspace was closed off the coast of North and South Carolina as the military carried out the operation on Saturday.

Footage on US TV networks showed the balloon falling to the sea after a small explosion.

An F-22 jet fighter engaged the high-altitude balloon with one missile - an AIM-9X - and it went down about six nautical miles off the US coast at 14:39 EST (19:39 GMT), a defence official told reporters.

US President Joe Biden had been under pressure to shoot the balloon down since it first appeared in US airspace last week.

The discovery set off a diplomatic crisis, with US Secretary of State Antony Blinken calling off an imminent trip to China over the "irresponsible act".

The Chinese authorities have denied it is a spying aircraft, and instead said it was a weather ship blown astray.

President Biden first approved the plan to down the balloon on Wednesday, but the Pentagon said it had decided to wait until the object was over water so as not to put people on the ground at undue risk.

Earlier on Saturday, Mr Biden told reporters he would "take care of it", in answer to a question about what would happen to the balloon, which was flying higher than commercial airline routes.

Soon after, the US Federal Aviation Administration (FAA) briefly paused all civilian flights at three airports around the South Carolina coast because of a "national security effort".

The coast guard also advised mariners to leave the area due to military operations "that present a significant hazard".

The military is now trying to recover debris which is spread over seven miles (11km), a military official told Reuters. Two naval ships, including one with a heavy crane for recovery, are in the area where the balloon fell.

China sought to play down the cancellation of Mr Blinken's visit over the balloon in a statement on Saturday, saying that neither side had formally announced a plan for a trip.

China's foreign ministry said Beijing "would not accept any groundless conjecture or hype" and accused "some politicians and media in the United States" of using the incident "as a pretext to attack and smear China."

According to US officials, the balloon floated over Alaska and Canada before appearing over the US state of Montana, which is home to a number of sensitive nuclear missile sites.

The incident angered top US officials, with Mr Blinken telling Beijing the balloon's presence was "a clear violation of US sovereignty and international law" and "an irresponsible act" on the eve of his visit to China.

America's top diplomat had been set to visit Beijing from 5 to 6 February to hold talks on a wide range of issues, including security, Taiwan and Covid-19. It would have been the first high-level US-China meeting there in years.

But plans faltered after American defence officials announced they were tracking a giant surveillance balloon over the US on Thursday.

On Friday, China finally acknowledged the balloon was its property, saying it was a civilian airship used for meteorological research, which deviated from its route because of bad weather.

And late on Friday, the Pentagon said a second Chinese spy balloon had been spotted - this time over Latin America with reported sightings over Costa Rica and Venezuela.

China has so far made no public comments on the reported second balloon. (BBC)

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