The United State is tracking a suspected Chinese surveillance balloon that has been spotted flying over sensitive sites in recent days.

Defense officials said they were confident the “high-altitude surveillance balloon” belonged to China. It was most recently seen above the western state of Montana. The military decided against shooting it down in case debris falls.  China warned against speculation and “hype” until the facts are verified.

Canada said today that it was monitoring “a potential second incident” involving a surveillance balloon, but did not say which country could be behind it.

It said in the statement that it is working closely with the US to “safeguard Canada’s sensitive information from foreign intelligence threats”.