A Canadian military spokesperson, a lieutenant named Steve Wills,
told BBC that it was difficult to target the balloon, even though it was about the size of a 25-story building, and that the failure to take it out wasn't embarrassing.
"With something like this, which is stationary in the air when the CF-18s are flying very, very fast, it is difficult to shoot it," Wills said.
The CF-18s were reportedly equipped with air-to-air missiles, but Canadian Major Roland Lavoie told AP the pilots refrained from using them.