The Pentagon says U.S. fighter jets shot down three unidentified objects from the skies above Alaska, Canada’s Yukon and Michigan over the weekend. A White House spokesperson said the objects posed a danger to civil aviation and were much smaller than a Chinese high-altitude surveillance balloon the Air Force shot down off the coast of South Carolina earlier this month. That incident prompted Secretary of State Antony Blinken to cancel a planned trip to Beijing. Over the weekend, the Commerce Department announced it would sanction six Chinese aerospace companies said to support China’s spy balloon program.

In Beijing, China’s Foreign Ministry said the U.S. illegally flew high-altitude balloons into Chinese airspace more than 10 times over the past year as part of a much broader spy program. Spokesperson Wang Wenbin said, “For the longest time, the U.S. has abused its own technological advantages to carry out large-scale and indiscriminate wiretapping and theft of secrets from all over the world, including from its allies.”

Meanwhile, when asked whether extraterrestrial aliens could be the source of the unidentified objects, the commander of the North American Aerospace Defense Command said, “I don’t rule out anything.”