Huh. I don’t get what you’re thinking, either. Interesting how two people can both think something is clear, yet not really know what the other is thinking.
Breaking down the question and applying it to what we know happened, as if the OP knew what had been reported about it:
“Is it possible that those false alarms going off in Hawaii and other places are not accidents…”
– Ok, so this would refer to the false public alarm, which is very clearly reported as being the result of one person thinking a drill was real.
” ... but rather planned exercises to test their systems for readiness?”
– So given what was reported, what would this mean? I can think of two things: 1) Dr. Strangelove devised a test where they tell one employee with a record of dubious competence to intentionally pretend not to understand the drill is a drill and send out a public warning, and not to let the emergency agency be prepared to issue a retraction quickly, to see what happens when the public and other governments start to panic about a missile warning. 2) Dr. Strangelove decides to run a drill where a missile warning is sent out and let sit for a bit, and then a cover-up story will be presented that it was just one employee messed up and no one thought about needing a retraction message available on short notice before.
It doesn’t sound to me like this is what the OP is asking, as the question details read:
“Since the threat of North Korea ?”
“This could be a way to test their warning systems, in case of a very real threat?”
Because such a test would not just test the warning systems, and if they wanted to do that, they could have it say it was a test in the initial message, and/or be ready to post a prepared retraction message right after that.
Now, there is one or two other questions which the OP does not seem to have in mind, which might be:
“Could this be a way to test what public and international reaction would be like following a public missile alert?”
– To which I would say, er yes, in theory, but it seems unlikely, particularly because of the risks involved for the relatively small intended gain.
or “Could this be a way to cause a public and international reaction for some perceived political or strategic gain?”
– To which I would say, um yes, in theory, though it’s reckless and hopefully not something that would be done. Our government and others have pulled false flag operations in the past. Even with the warmonger clown in the White House, I like to think this isn’t something that would be done, and it does seem much more plausible that it was just a mistake as has been reported in fairly convincing detail so far.