Given our vast unspoken "eye in the sky" capability;
Unless they hand carried every little piece of each missile, into these locations, at night, under cloudy conditions, and assembled them in place...I'm pretty sure they left tire tracks, broken/fallen trees, or some kind of evidence of their activity near the placements.
And I'll bet we've been watching them for a long, long time.
You?
Yet—
Any war is hard and your own people will die. So to go off to war—or a campaign—or even a strike—without considering the consequences, is gross malpractice.
The fact of the matter is North Korea is decidedly not an easy nut to crack or we would have cracked it long ago.
They have capabilities that need to be countered or eliminated.
A swift, rapid strike without far more forces in place than right now would not take out all of their capabilities and our military knows it.
For one, we need to have a huge stockpile of MOABs—and we do not. I hope the manufacture of these vital weapons is at the highest capacity right now!
We need to allocate a strike on every tunnel mouth and camouflaged valley we know about—and there are over 10,000 or so—and get them targeted and hit in the first 48 hours.
Now that is ideal and we wouldn't be able to do it with ALL our existing forces over the entire globe. So we need to prioritize the most likely targets to hit first. Our satellite capabilities would be prime resources here just as you mentioned—still— but--we cannot be certain until we strike. And any we miss will be used against us and our allies and civilians. Many people will die and the press will immediately begin their criticism.
Actually, the only way to really immediately neutralize the NORKs would be to use our own nuclear weapons and hit them with a mass attack.
I just can't see the political will to do so, even from Trump. Hell, the world is still bitching at us for dropping two on Japan, which has been proven to be justified thousands of times, but all the logic in world has no effect on them.
We could just ignore them and press on with such an attack, but we then have to be prepared for the aftermath.
Frankly, this nation just don't have the will. You do; I do, but the vast unwashed will be lead into the Thunderdome to demand the head of Trump.