WASHINGTON — A U.S. F-22 fighter shot down a third unmanned aircraft in a week on Saturday, this time over northern Canada, according to a U.S. official.

In addiation, the Federal Aviation Administration and NORAD restricted airspace in central Montana Saturday and scrambled fighter jets after radar detected an unidentified object, NORAD announced late Saturday. Pilots did not identify an object that correlated with the radar signals and airspace was reopened. NORAD will continue to monitor the area, according to a statement.

The actions highlight the heightened tensions regarding incursions in U.S. airspace since the Chinese spy balloon and two other unidentified objects were discovered in the last week. 

The downing came as U.S. troops sought to recover a car-size object shot down Friday over Alaska. The three objects, including the Chinese spy balloon that drifted across sensitive military sites in the continental United States, have strained relations between the Americans and Chinese.

It’s not clear who operated the objects shot down Friday and Saturday, according to the U.S. official, who was not authorized to speak publicly. 

Canadian Prime Minister Justin Trudeau also announced the news on Twitter Saturday. Trudeau said in a tweet he had spoken to U.S. President Joe Biden. 

“I ordered the take down of an unidentified object that violated Canadian airspace,” Trudeau said. North American Aerospace Defense Command then “shot down the object over the Yukon.”