Windward_Side, I agree with all your concerns.

Definitely have to factor in "what ifs" into any type of military "test" or "exercise".

The problem is that NK interprets and factors in "what ifs" to US military exercises the same way we must factor in "what ifs" to NK missile tests.

NK has backed off missile "tests" to the waters around Guam.  Clearly, the trade-off demanded by NK (and China and Russia) is that the US cancel military exercises in South Korea.

So, what happens if the US, put in this predicament directly and precisely by Trump's big body threats (I note that the US just carried out the same type  of exercises a few months ago, without the same implications - Russia and China well publicized and joint with NK objections).

Trump did that.  What will Trump do next?  In the face of a coalesced China-Russia-NK objection? 

No what ifs on that one, in my view.  The we are backed into a corner.  The US carries on military exercises, it justifies further NK missile tests . .