FOG BLOG CANADA LOG: U.S. MILITARY SHOOTS DOWN YET ANOTHER HIGH ALTITUDE OBJECT OVER LAKE HURON!

U.S. shoots down flying object over Lake Huron near Canadian border Meanwhile, Canadian investigators are hunting for the wreckage of an unidentified flying object that was shot down by a U.S. jet over Yukon territory on Saturday.

"Recovery teams are on the ground, looking to find and analyze the object," Prime Minister Justin Trudeau told reporters on Sunday.

"The security of citizens is our top priority and that's why I made the decision to have that unidentified object shot down," he said, adding that it had posed a danger to civilian aircraft.

North America has been on high alert for aerial intrusions following the appearance of a white, eye-catching Chinese airship over American skies earlier this month.

The 200-foot-tall (60-metre-high) balloon - which Americans have accused Beijing of using to spy on the United States -- caused an international incident, leading Secretary of State Antony Blinken to call off a planned trip to China only hours before he was set to depart.

Surveillance fears appear to have U.S. officials on high alert.

Twice in 24 hours, U.S. officials closed airspace -- only to reopen it swiftly.

On Sunday, the Federal Aviation Administration briefly closed space above Lake Michigan. On Saturday, the U.S. military scrambled fighter jets in Montana to investigate a radar anomaly there.

Canada also closed airspace on Sunday near Tobermory, Ontario, which is on Lake Huron near the U.S. border, according to Nav Canada, a private non-profit that operates Canada's air traffic control system.

China denies the first balloon was being used for surveillance and says it was a civilian research craft. It condemned the United States for shooting it down off the coast of South Carolina last Saturday.

At least three other flying objects have been destroyed over North America since then, as military and intelligence officials focus on airborne threats.

U.S. Senate Majority Leader Chuck Schumer told U.S. broadcaster ABC that U.S. officials think two of the latest objects were smaller balloons than the original one, which was brought down off the coast of South Carolina on Feb. 4.

A second was shot down over sea ice near Deadhorse, Alaska, on Friday. The third was destroyed over the Yukon on Saturday.

The White House said only that the recently downed objects "did not closely resemble" the Chinese balloon, echoing Schumer's description of them as "much smaller."

"We will not definitively characterize them until we can recover the debris, which we are working on," a spokesperson said.

Schumer said he was confident U.S. investigators scouring the ocean off South Carolina to recover debris and electronic gadgetry from the original balloon would get to the bottom of what it was being used for.