How is it that these Korean bottle rockets are ICBMs?
Wouldn’t they need to travel to another continent to be “intercontinental”?
They launch them on a nearly vertical trajectory to test the range vs a more horizontal course which may draw return fire.
Our return fire wouldn’t be inert test rounds, but most likely the contents of a boomer sub.
If they can get to a certain orbital height, they’re considered ICBMs because that automatically gives them a certain potential range. It’s like with your car - if your car has a certain unrefueled range, it’s technically an interstate transport vehicle even if all you do is drive around your town.
By knowing how high it will go the horizontal range can be calculated.
Think of it this way: Awkwardness aside, if I can throw a rock almost straight up, very high, I can also, if I choose, throw it a long horizontal distance by altering my release angle to, say, 40 degrees.
Given the energy in the booster, one has a range of solutions / options.
Strictly speaking, if bottle rockets are legal where you live, you can demonstrate the same thing with them. :-)