Usa news: The objects may be “tied to commercial or research entities and therefore benign”, spokesman John Kirby said.

US and Canadian officials have not yet located or recovered any wreckage from the three downed aircraft.

Beijing earlier accused the US of “a trigger-happy overreaction”.

China has denied one of its balloons, which was destroyed by a US fighter jet earlier this month off South Carolina, was being used for espionage, saying it was merely a weather-monitoring airship that had blown off course.

At Tuesday’s daily news conference, Mr Kirby said it will be difficult to determine the purpose or origin of the three other objects that were destroyed over Alaska, Canada and Michigan until the debris is found and analysed.

“We haven’t seen any indication or anything that points specifically to the idea that these three objects were part of the PRC’s [People’s Republic of China] spying programme,” the White House National Security Council told reporters, “or that they were definitively involved in external intelligence collection efforts”.