US closes Lake Michigan airspace citing 'national defense': FAA

US officials restricted the airspace over Lake Michigan on Sunday citing a potential new threat to national security, as the United States and Canada respond to a series of recent air intrusions.

The Federal Aviation Administration 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.