That way, the rest of us (as in U.S.) can get on with the job of fighting and winning any wars that come our way, and the scholars can debate it after the fact.
There is no war with North Korea for all practical purposes right now. If Congress wants to authorize first use, there is nothing stopping them, but for the gutlessness of our leaders that you (rightly) so fear that you will assume the latitude for a Republican President against North Korea that you would otherwise rightly fear in the likes of Clinton when he went to Kosovo. It is hypocritical to criticize the latter while assuming the necessity of the former. If we had a Congress with any principal or intellect, we wouldn't be having this discussion because the need for preemptive contingencies would already be under discussion. The Constitutional principal requiring the support of the people through their representatives in Congress before going to war is not something you can just blow away for political or military convenience. It is unnecessarily handing our political enemies on the left a weapon against us, that may well hamper the President in the future. It isn't necessary and that is my concern.
By putting the power to declare war in the hands of Congress, the Constitution, as a limiting document, did not give the President the power to initiate war on his own. It is so obvious that to say otherwise is mere obfuscation.
First use of nuclear weapons is an act of war. It is not blowing a ship on the high seas. It is not defending the homeland directly. It is not a defense of American assets abroad when they have not been attacked. If the nature of war has changed such that Congressional authorization is no longer practical, then amend the Constitution, else we do not operate under even the pretense of the rule of law.
Intercontinental ballistic missile technology and state-sponsored international terrorism have forever changed the legal nature of war. One obviously cannot wait until the beastie is in the air and confirmed to be a nuke before calling Congress into session for a vote so that our military can respond. So, the obvious thing to do is to pass enabling legislation authorizing first use against North Korea if the President has determined that there is an imminant threat of first use OR amend the Constitution as appropriate. The former is an obvious thing to do given Kim Jong Il's multiple violations of agreements, his actions, and his statements.
So, why do you fear that?
If the Congress won't do that then the President has some selling to do. If the American people won't support the Congress in passing a contingency plan then we deserve what we get. Punching the button every time the President perceives a threat is a precedent that justifies surprise nuclear attacks against us. It gives a President Hillary tools I really don't want her to have. (I would bet any money that you two were bitching about Bubba's cruise missiles into the Sudan, much less his illegal war in Kosovo.) Such actions would consolidate and deepen international hatred for the United States including acts of war. If that's the world you want, you have made yourself clear. It's a heck of a position to take when we now have plenty of time and latitude to discuss our options on the Korean peninsula in open Congressional debate.
You really need to try the decaf there.
And let's get something straight: I do not "fear" anything except God Almighty, although I do subscribe to Will Rogers famous maxim about "no man or his property is safe when the Congress is in session" (paraphrased).
Now moving right along here, the best defense is a good offense, and the Israelis have had no problem with preemptive strikes, and you can bet your ass that if they knew that Iran or Syria were preparing to lob a nuke in their direction, they would preempt them with their own nukes on Damascus and/or Tehran. That IMHO, is a real possibility, but more likely from Iran, which has truly demonic leadership in charge, compared to Syria, which has truly buffoonish leadership in the form of ASSad (rhymes with Asshat) Jr.
Now if, on the other hand you wish to subscribe to the idea that America must not preemptively strike first (be it conventional OR nuclear), then you will need to face the fact that should that day dawn that America is sucker punched with a nuke on our own soil, that the sage prediction of no less than retired General Tommy Franks will come true: we will have an unlimited state of martial law declared, we will cease to be a true Republic, and the military will be running the Country.
That means that all of your Constitutional contemplations will become moot.