As US Navy divers are working to recover what is left of the balloon, a Notre Dame Law Professor is breaking down what this means for relations between the US and China.
Mary Ellen O'Connell says spying is nothing new, but anyone trying to carry out intelligence must stay outside the 12-mile territorial sea boundary.
Which would make it unusual if this stray balloon was an accident, as China said.
"China's been denying and saying this was a weather balloon and it turns out that yes, the US government has been right, it was a surveillance balloon with very sensitive data, I think the US government is particularly interested in what China thought it could get using the balloon that it could not get with satellites or with aircraft flying close to the US borders," said Mary Ellen O'Connell, University of Notre Dame International Law Professor.
And while China claims the US' response conflicted with international practice, O'Connell says the US was within its rights to shoot the balloon down.