The U.S. military shot down at least three unidentified flying objects over the weekend after a Chinese spy balloon that had invaded American airspace was downed on Feb. 4, setting off a diplomatic crisis.
It is unclear what the objects were, what their purpose was or who sent them. On Tuesday, a spokesman for the National Security Council said the objects might turn out to be harmless commercial or research efforts that posed no real threat to the United States, though White House officials have said they posed a тАЬvery realтАЭ threat to civilian air traffic.
Regardless, the United States and Canada have become hypervigilant since the balloon incursion. The North American Aerospace Defense Command has adjusted its radar system to become more sensitive, sharply raising the number of objects it detects.
HereтАЩs a quick timeline of events.
Feb. 4
A Chinese spy balloon is shot down over the Atlantic Ocean.
The balloon entered Alaskan airspace on Jan. 28, Pentagon officials said, and later drifted from Idaho southeast to the Carolinas before it was shot down off the coast of South Carolina.
The balloon was about the size of three buses and was flying at an altitude of 60,000 to 65,000 feet.
The incident prompted Secretary of State Antony J. Blinken to cancel a trip to China that would have been the first by a Biden cabinet secretary.
American officials have said they believed the balloon was meant to conduct surveillance on U.S. military bases, although China has maintained that the device was a civilian aircraft that strayed into American airspace. On Monday, a Chinese official said unauthorized balloons from the United States had flown over Chinese airspace more than 10 times since the start of last year.
Feb. 10
A U.F.O. is shot down off Alaska.
A U.S. fighter jet brought down an unidentified object over the waters of Alaska. The object broke into pieces after being shot down and was most likely not a balloon, a Defense Department official said. A White House official said the object was the size of a small car.
The object was first detected on Thursday night, Alaskan time, and was headed toward the North Pole before it was struck down.
Feb. 12
A U.F.O. is shot down over Lake Huron.
An object that first appeared over Montana on Saturday reappeared the next day before being shot down over Lake Huron, off Michigan. The object, which was flying at about 20,000 feet, had an octagonal structure with strings hanging off it but had no discernible payload, U.S. officials said.
Remy Tumin contributed reporting.
