US Air Force General Glen D. VanHerck, commander of the North American Aerospace Defense Command (NORAD), in a period of 7 months went from saying he would be able to spot UFOs/UAPs to essentially saying we can’t spot balloons in our skies. Here are quotes by Gen. VanHerck:

I’ve Yet To Find One That Had Aliens,” Says NORAD Boss About UAP - July 22, 2022

First of all, let's be clear. My job as the NORAD commander is to identify every single UAP or ...whatever it is. What I would report to you is I've yet to find one that had aliens or was a spaceship that we've identified.
If any of our NORAD fighters or, or any assets assigned to NORTHCOM, came across some type of UAP, we would absolutely report that. I’m just telling you, we haven't seen that.

NORAD Commander Blames 'Domain Awareness Gap' for Earlier Chinese Balloon Incursions - Feb 7, 2023

So those balloons, so every day as a NORAD commander it's my responsible to -- responsibility to detect threats to North America. I will tell you that we did not detect those threats.
And that's a domain awareness gap that we have to figure out. But I don't want to go in further detail.

The need to take UAP seriously

Christopher Mellon, former Deputy Assistant Secretary of Defense for Intelligence, attributes the issue to filters that only show predetermined things to the operators.

Senator Kirsten Gillibrand echoed those concerns, raising the need to take Unidentified Aerial Phenomena (UAP) seriously.

The Invisible Gorilla

There is a famous psychological experiment where people are asked to watch a video of people passing basketballs and to count the number of times the ball was passed by one group. At one point, a person in a gorilla suit walks into the middle of the basketball players, faces the camera, beats his chest, and then walks off.

Roughly half the people miss the gorilla.

It is a phenomena called inattentional blindness.

(see Bet You Didn't Notice 'The Invisible Gorilla', NPR)

If these spy balloons have been floating across our skies without being detected by our military, what other “gorillas in the skies” (or oceans) might the military be missing?