The downing of a huge Chinese balloon off the US coast, followed by the shootdowns of two smaller objects over Alaska and Canada – and another over Michigan on Sunday – has raised concerns about North American security and further strained relations with China.
Here is what we know so far:
What were the four objects?
The story begins in late January, when a giant Chinese balloon – which US officials have said was a surveillance balloon – drifted for days through US skies before being shot down on 4 February by an F-22 jet off the South Carolina coast. China insisted the balloon was conducting weather research.
The Pentagon said it had a gondola the size of three buses that weighed more than a ton; that it was equipped with multiple antennas, and had solar panels large enough to power several intelligence-gathering sensors.
Then Friday 10 February, US fighter jets downed another object off northern Alaska, the military said, adding it was “within US sovereign airspace over US territorial water”. It lacked any system of propulsion or control, officials said.
On Saturday, a US F-22 jet, acting on US and Canadian orders, downed a “high-altitude airborne object” over Canada’s central Yukon territory, about 100 miles (160km) from the US border, saying it posed a threat to civilian flight. Canada described it as cylindrical and smaller than the initial balloon. Canadian defence minister Anita Anand would not speculate on whether it originated in China.
Officials described the second and third objects as about the size of a Volkswagen Beetle.
On Sunday, US president Joe Biden ordered US warplanes to down an unidentified object over Lake Huron in Michigan “out of an abundance of caution”, a senior administration official said.
The object was described as an octagonal structure with strings hanging off it, and was not deemed to be a military threat to anything on the ground, but could have posed a hazard to civil aviation because it flew at about 20,000ft (6,000 metres), the official said.
US Senate majority leader Charles Schumer, who was briefed by the Biden administration after the incident over the Yukon, said on Sunday – before the Lake Huron incident – that the previous two objects were likely balloons, “but much smaller than the first one”, both flying at about 40,000ft (12,200 metres).
Only the first object so far has been attributed to Beijing.
The US military commander who safeguards US airspace said on Sunday he could not determine how the latest three objects shot down over the past three days were staying aloft, adding he was not calling them balloons for a reason.
What has been recovered?
Military teams working from planes, boats and mini-subs are scouring the shallow waters off South Carolina for the first object, and military images showed the recovery of a large piece of balloon. The Federal Bureau of Investigation is taking custody of the debris for analysis.
Operations to recover the second object continue on sea ice near Deadhorse, Alaska. “Arctic weather conditions, including wind chill, snow and limited daylight, are a factor,” the military said.
Recovery teams backed by a Canadian CP-140 patrol aircraft are searching for debris from the third object in the Yukon, Anand said on Saturday.
The Pentagon said the FBI was working closely with Canadian police.
US military personnel equipped with specialist diving gear designed for the extreme cold waters of Michigan’s Lake Huron are expected to be deployed quickly to search for pieces of the destroyed fourth object.
Why so many objects now?
The United States has said the balloons were part of a “fleet” that has spanned five continents. Some analysts say it may be the start of a major Chinese surveillance effort targeting foreign military capabilities ahead of possible acute tensions over Taiwan in coming years.
Analysts said US and Canadian intelligence constantly receive huge amounts of raw data, and generally screened some out to focus on the threat of incoming missiles, not slow-moving objects such as balloons.
“Now, of course, we’re looking for them. So I think we’re probably finding more stuff,” Jim Himes, the top Democrat on the House intelligence committee, told NBC.
The Pentagon has said it is more closely scrutinising the radar since the balloon discovery.
Officials have said three balloons are now known to have briefly overflown US territory during Donald Trump’s administration – undetected at the time – and one earlier in Biden’s term.
What’s the impact on US-China ties?
The United States scrapped US secretary of state Antony Blinken’s China visit, intended to stabilise severely strained relations, and has sanctioned six Chinese entities believed to support military spy balloon programs.
Beijing denounced the downing of the first balloon, saying it “seriously violated international practice”. It reserved the right “to use necessary means to deal with similar situations”.
There has been no Chinese reaction to the latest downings.
