Chinese balloon sensors recovered from ocean, says US

Search crews found "significant debris from the site, including all of the priority sensor and electronics pieces identified", said US Northern Command.

The FBI is examining the items, which the US says were used to spy on sensitive military sites. 

The US has shot down three more objects since the first one on 4 February.

"Large sections of the structure" were also recovered on Monday off the coast of South Carolina, military officials say.

About 30-40ft (9-12m) of the balloon's antennas are among the items found, according to CBS, the BBC's US partner.

US officials said the high-altitude balloon originated in China and was used for surveillance, but China said it was merely a weather-monitoring airship that had blown astray. 
 

Since that first incident, American fighter jets have shot down three more high-altitude objects in as many days - over Alaska, Canada's Yukon territory, and Lake Huron on the US-Canada border.

In the Lake Huron strike, the first Sidewinder missile fired by the US F-16 warplane missed its target and exploded in an unknown location, US media reported, citing military sources. The second missile hit the target, according to reports.

Each Sidewinder missile costs over $400,000 (£330,000).

• Strange flying objects - unanswered questions

Officials have said the slow-moving unidentified objects, all of which have been smaller than the first balloon, may be difficult for military pilots to target. 

White House spokesman John Kirby said on Monday the three other objects were shot down "out of an abundance of caution".

They did not pose "any direct threat to people on the ground", but were destroyed "to protect our security, our interests and flight safety", he said.

The balloon shot down over South Carolina was described by officials as the size of three buses. 

The second object, over Alaska, was described by officials as the size of a "small car". The third object, over the Yukon, was "cylindrical". And the fourth, over Michigan, was said to be "octagonal" with strings attached. 

A Pentagon memo later reported in US media said the flying object shot down over Yukon appeared to be a "small, metallic balloon with a tethered payload below it". 

Defence officials also wrote in the memo that the object shot down in Michigan "subsequently slowly descended" into the water after impact.