Pentagon says the balloon is heading east and rejects China claim that it was not for spying.
A Chinese spy balloon has changed course and is now floating eastward at about 60,000 feet (18,300 meters) over the central United States, demonstrating a capability to manoeuvre, the US military said.
The disclosure about the spy balloon's manoeuvrability directly challenges China's assertion that the balloon was merely a civilian air ship that had strayed into US territory after being blown off course.
"We know this is a Chinese (surveillance) balloon and that it has the ability to manoeuvre," Air Force Brigadier General Patrick Ryder told a news briefing at the Pentagon, declining to say precisely how it was powered or who in China was controlling its flight path.
US President Joe Biden on Wednesday decided against shooting down the balloon as it floated over Montana due to US military concerns about the likely dispersal of debris, American officials say.
The Pentagon expects the balloon to continue travelling over US airspace for a few more days, Ryder said, declining to speculate on what options the US military might develop in that time as speculation swirled about whether Biden could still order the balloon be destroyed or perhaps captured.
Ryder said the US military would not specify where precisely the balloon was positioned over the central United States, saying he didn't want to get into an "hour-by-hour" cycle of updates.
Ryder added the balloon posed no risk to people on the ground.
He spoke amid growing political fallout over the Chinese balloon's presence in the United States.
In response to the spy balloons, China's Foreign Ministry says the country is a responsible state and acts in accordance with international law pic.twitter.com/4FWyhwfwaD— TRT World Now (@TRTWorldNow) February 3, 2023
The postponement of US Secretary of State Antony Blinken's trip, which had been arranged in November by Biden and Chinese President Xi Jinping, is a blow to those on both sides who saw it as an overdue opportunity to stabilize an increasingly fractious relationship.
The last visit by a US secretary of state was in 2017.
Biden ignored questions about the balloon when giving remarks on the economy Friday morning.
Chinese spy satellites carry similar sensors to what US officials believe is on the spy balloon, raising questions about why Beijing would risk such a brazen act on the eve of a major diplomatic event.
Still, the Chinese spy balloon has taken a flight path that would carry it over a number of sensitive sites, officials say.
One such site could be military bases, including in Montana, which is home to intercontinental ballistic missile silos.
The Billings, Montana, airport on Wednesday issued a ground stop as the military mobilised assets including F-22 fighter jets in case Biden ordered that the balloon be shot down.