In light of the possible attack on North Korea, I will share a few thoughts. Without any political analysis, purely from a technical military standpoint: the balance of power and weighing of threats, so to speak.
1) If the United States does decide to attack North Korea, there will be no talk of a ground operation (not by the U.S., nor its allies). An exception is a conflict of mutual destruction with the use of weapons of mass destruction. Thus Vietnam will seem like a walk in the park.
The Koreans have over 1 million people in their regular army (with 24 million inhabitants). The average service time is five to seven years. Imagine the sort of fighter one could train (plus ideology and high morale and psychological levels). Another 7 million could be drafted; if not immediately, then very quickly.
The Koreans have a colossal infrastructure built up underground. The Koreans, at the moment, have about 90,000 soldiers who are in the special forces, and of those, at least seven brigades are snipers. A significant portion of the country's landscape is mountainous.
These are just a few sketches of a portrait of the North Korean army.
Oh, and also, the Americans can only dream of a mass betrayal and desertion of the Koreans, fondly remembering Iraq in 2003. Bribery of the generals — same thing.
2) On the issue of striking with “Tomahawks" and aircraft power. Here the power is clearly on the side of the United States. However, one should not forget that the DPRK has about 80 submarines of various classes, including midget submarines, and those that could launch a ballistic missile from a submerged position.
It is also not so one-sided when it comes to Korean air defense. On the one hand it is extremely outdated, but on the other it is nearly the largest in the world. It is the same story with its Air Force.
It is an open question as to whether monetary quantity converts into quality; however, there's no question that neither aviation nor the Tomahawks will have a carefree time in the skies, like in Iraq in 2003.
3) Will the DPRK respond with a nuclear strike? In my view, this is a real possibility. Active defense is the core of the Korean military doctrine. However, a first attempt at aggression could be made by the air and naval forces. Further development of the situation depends on its success.