Security experts said that China's flight of a suspected spy balloon over the United States appears to be a more aggressive espionage tactic than relying on satellites and the theft of industrial and defence secrets.
For decades, the US and China have used surveillance satellites to keep an eye on each other from the air.
But China's recent balloons -- a White House official said Friday's February 3 episode was not the first -- have some in Washington scratching their heads.
It's more amateurish, said former White House national security adviser John Bolton. Do the cameras in their satellites have high enough resolution to send a balloon over? The uproar over the balloon comes as China has been building up its military capabilities and challenging America's military presence in the Pacific.
The United States believes that Beijing tries to extract proprietary information and knowledge from American companies.
China said the balloon was intended for civilian meteorological and scientific purposes that strayed into US airspace, and on Saturday accused American politicians and media of taking advantage of the situation to discredit China.
The balloon discovered on Friday appeared deliberately provocative, according to Dean Cheng, senior advisor to the Chinese programme at the US Institute of Peace, a former rebuffed accusations of espionage, and said the US holds a Cold War mentality and hypes up the China threat.