The U.S. is tracking a Chinese spy balloon flying within U.S. airspace for several days.

According to NBC News, the Pentagon decided not to shoot it down because falling debris could harm someone on the ground.

A Pentagon official told reporters that the Defense Dept. has “very high confidence” it is a Chinese high-altitude balloon. And that its purpose is to fly over to collect sensitive information from military sites.

On Wednesday, US military leaders, including Defense Secretary Lloyd Austin and General Mark Milley, the US Joint Chiefs of Staff chairman, met to assess the threat. 

A senior defense official claims no "significantly enhanced threat" exists to any US intelligence or information because officials "know exactly where this balloon is and exactly where it's passing over."

According to the official been spotted overhead in the US in the past few years.

But this particular balloon "is appearing to hang out for a longer period of time" and is "more persistent" than previous Chinese spy crafts.

Even though a decision was made not to blow the spycraft out of the sky, the option remains open.

Chinese spy balloon over U.S.

The flying spycraft made its way over Alaska's Aleutian Islands and flew above Canada before it appeared over the city of Billings, Montana, on Wednesday, officials claimed.

"There have been reports of pilots seeing this thing even though it's pretty high up in the sky," one defense official claimed."So you know, it's, it's sizable." But in videos of the flying object, it sometimes appears to be flying lower. 

Widespread sightings led the Billings Logan International Airport to shut down air traffic closing 50 sq miles of air space for two-hours.

Montana is home to one of three U.S. nuclear missile silo fields, which is based 250 miles southwest of Billings at Malmstrom Air Force Base. 

Thursday at the Pentagon, officials would no longer disclose the location of the Chinese surveillance aircraft. And they would not provide details of the aerial vehicle including a description or its size.

The US has allegedly raised the matter with Chinese officials in their embassy in Washington DC and with the Chinese leaders in Beijing.