A Chinese spy balloon, as big as “three buses” was spotted over the United States' airspace, the Pentagon said, adding that it is tracking its movements. US President Joe Biden has been briefed about the incident, a senior defence official said.
The spotting of the object comes days before US Secretary of State Antony Blinken’s visit to Beijing, in a rare China visit by a top American diplomat.
"The United States government has detected and is tracking a high-altitude surveillance balloon that is flying over the continental United States right now," Pentagon spokesperson Brigadier Gen Pat Ryder said.
The balloon was spotted over Montana on Thursday. Authorities did not shoot down the balloon fearing it would endanger too many people on the ground, a senior defence official said.
The balloon was travelling at an altitude well above commercial air traffic and does not present a military or physical threat to people on the ground, Pentagon said.
US officials brought up the issue with their Chinese counterparts through diplomatic channels in Beijing and in Washington. "We have communicated to them the seriousness with which we take this issue," a US official said.
Blinken is expected to travel to China next week for a visit agreed to in November by Biden and Chinese President Xi Jinping. It was not clear how the discovery of the spy balloon might affect those plans.
Relations between China and the United States have soured in recent years, particularly following then-US House Speaker Nancy Pelosi's visit to Taiwan in August, which prompted dramatic Chinese military drills near the self-ruled island.
Since then, Washington and Beijing have sought to communicate more frequently and prevent ties from worsening.
(With inputs from Agencies)