After a Chinese spy balloon was brought down this month
source: nytimes.comthe U.S. has shot down at least three unidentified flying objects recently
source: nytimes.comThe U.S. military shot down at least three unidentified flying objects
source: nytimes.comUnited States and Canada have become hypervigilant since the balloon incursion
source: nytimes.comIt is unclear what the objects were
source: nytimes.comThe North American Aerospace Defense Command has adjusted its radar system
source: nytimes.comsharply raising the number of objects it detects
source: nytimes.com