Washington, 3 February 2023 (dpa/MIA) - Washington insists the Chinese aircraft flying over Montana is a spy balloon, after Beijing claimed it was a civilian airship.

"We know it's a surveillance balloon," US Defense Department spokesman Pat Ryder said, without providing further details.

He made it clear that the Pentagon is standing by its assessment of the incident.

He also said the balloon was highly manoeuverable, after Beijing cited difficulties in steering it amid Westerly winds.

The aircraft is expected to continue flying over US territory for several days, he said.