Washington: US officials restricted the airspace over Lake Michigan on Sunday citing a potential new threat to national security but soon reopened the skies, as the United States and Canada respond to multiple air intrusions.
The Federal Aviation Administration (FAA) announced "temporary flight restrictions" over one of the Great Lakes along the US-Canada border, designating it as "national defense airspace," one day after a similar closure over Montana led to the scrambling of US fighter jets.
The Montana closure was ordered over a "radar anomaly," but no object was discovered.
Similarly, the Lake Michigan restrictions were lifted shortly after they were announced, apparently with no threat detected.
"The FAA briefly closed some airspace over Lake Michigan to support Department of Defense activities. The airspace has been reopened," the agency said in a statement to AFP.
Sunday's action over Lake Michigan marked the latest move to address a series of potential national security threats that began in late January with the discovery of a Chinese balloon - dubbed a spy craft by US officials - traversing the United States at high altitude.
It was eventually shot down February 4 by an F-22 jet off the South Carolina coast.
Last Friday US fighter jets downed another object off northern Alaska, the military said, adding it was "within US sovereign airspace over US territorial water." It lacked any system of propulsion or control, officials said.
And on Saturday a US F-22, acting on US and Canadian orders, shot down a mysterious, cylindrical "airborne object" over Canada's Yukon territory about 100 miles (160 kilometers) from the US border, saying it posed a threat to civilian flight.
Calls have grown meanwhile for President Joe Biden to provide a detailed account to the American people of the nature of the objects, the potential threats to the homeland, and what Washington has planned to prevent more such missions.