The US military is tracking a suspected Chinese spy balloon that has been flying over northwestern America in recent days.
A senior defence official said the US has “very high confidence” it is a Chinese high-altitude balloon and was flying over sensitive sites to collect information.
“Clearly the intent of this balloon is for surveillance,” the official said.
Beijing did not immediately deny it belonged to them.
Chinese foreign ministry spokesperson Mao Ning said: “We are learning about the verification of this matter.
“We hope both sides can handle the matter calmly and prudently.
“I would like to emphasise that until the facts are clarified, speculation and hype will not be helpful to the proper resolution of the issue.”
The balloon was spotted over Billings, Montana, on Wednesday – close to one of the US’s three nuclear missile silo fields at Malmstrom Air Force Base.
It also flew over the Aleutian Islands, off the coast of Alaska, and through Canada.
The balloon is still in US airspace but officials declined to say where it is now.
They acknowledged it was operating above civilian air traffic and below “outer space” but declined to say how high it was flying.
Military and defence leaders have considered shooting the balloon out of the sky but decided against it due to the potential safety risk from falling debris.
US defence secretary Lloyd Austin convened a meeting of senior military and defence leaders to review the threat profile of the balloon and possible responses, which were presented to US President Joe Biden on Wednesday.
The US has engaged Chinese officials “with urgency” and communicated the seriousness of the situation.
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Pentagon press secretary Brigadier General Patrick Ryder said: “The United States government has detected and is tracking a high-altitude surveillance balloon that is over the continental United States right now.
“The US government to include NORAD (North American Aerospace Defense Command), continues to track and monitor it closely.
“The balloon is currently travelling at an altitude well above commercial air traffic and does not present a military or physical threat to people on the ground.
“Instances of this kind of balloon activity have been observed previously over the past several years.
“Once the balloon was detected, the US government acted immediately to protect against the collection of sensitive information.”
‘Potential second incident’
Canada’s national defence said Canadians are safe and that officials are taking steps to ensure the security of its airspace, including the monitoring of “a potential second incident”.
“NORAD, the Canadian Armed Forces, the Department of National Defence, and other partners have been assessing the situation and working in close coordination,” the statement said.
“Canada’s intelligence agencies are working with American partners and continue to take all necessary measures to safeguard Canada’s sensitive information from foreign intelligence threats.
“We remain in frequent contact with our American allies as the situation develops.”
China and the US have experienced tensions of late, clashing over Taiwan and China’s human rights record and its military activity in the South China Sea.
US Secretary of State Antony Blinken is expected to travel to China in the coming days.
It is not clear if this will affect his travel plans, which the State Department has not formally announced.