As I noted on Wednesday, Guam is well protected against a prospective North Korean ballistic missile assault. But what if an attack on Guam did occur?

In that scenario, while it's impossible to know how President Trump would respond, I believe the U.S. military would recommend retaliation at one of four levels.

First, in the event that a missile strike caused no or very few casualties (less than 5), the U.S. would likely employ measured retaliation. North Korean launch sites and missile units would be destroyed, but the regime's command and control facilities would probably be left alone. Neither would the U.S. be likely to target North Korea's leadership. Instead, the overriding intent would be the removal of the ballistic missile threat and the restored U.S. balance of power. If the North Koreans attempted to reconstitute their ballistic missile program, the U.S. would destroy it again.

What if a North Korean strike inflicted casualties beyond the low digits but not in the hundreds or thousands?

In that case, I believe the U.S. would target North Korean command and control elements as well as missile forces. This would almost certainly entail air- and sea-based missile engagement of command facilities across North Korea, including facilities in and around Pyongyang. Via these operations, the U.S. would want to cultivate North Korea's perception that further aggression would mean their annihilation. But it would also intend to achieve North Korea's submission to a new balance of power far more weighted to U.S. and South Korean interests.

Third, if a missile incident imposed major casualties but was not nuclear in nature, the U.S. would pursue the fundamental debilitation of North Korea's means of resistance.

We would see massive attacks on the North's air, artillery, radar, and logistical support forces. In the first instance, the U.S. would probably hold off targeting Kim Jong Un himself, but would attempt to decapitate his senior commanders. The intent of that qualification would be to leave space for a diplomatic arrangement in which Kim Jong Un transferred power to a transitional government. Still, the U.S. would demand the transitional government was at least semi-pro American.

Nevertheless, alongside the immediate debilitation operations, the U.S. military would also surge personnel and equipment into the region. This forward deployment would entail not just Airborne and Marine maneuver divisions, but most of the Army's armored heavy brigades. Aside from some units held to deter Russian or Iranian aggression, the military would also redeploy the bulk of its air and naval forces to Guam, Okinawa, and Japan. I would, for example, expect five or six carrier groups to head toward North Korea as soon as possible.

This buildup would present Kim and China with an unmistakable expression of American military supremacy. Although this power projection capability has not been manifested in many years, it remains the unique identifier of U.S. military. In turn, North Korean military figures would face one of two choices: overthrow the Kim dynasty, or die. And beyond clarifying to China that U.S. personnel would not cross the Yalu River, there would be little attention paid to Chinese political interests. From the strategic perspective, China would have burned its rights to American concern by failing to restrain their North Korean ally.

Finally, there's the doomsday case of a North Korean attack involving nuclear weapons. In the event that a nuclear warhead hits Guam, the U.S. would almost certainly respond with massive nuclear retaliation. North Korean military targets would be the first priority, but Trump would also be given an option to destroy Pyongyang. Regardless, Kim and all those around him would be a dead man. The U.S. would enforce Korean unification on American terms.

Ultimately, whatever form a North Korean attack on Guam took, the consequences for Kim would be profoundly negative. Determined to protect its citizens and preserve a deterrent posture in the 21st century, the U.S. military would recommend to Trump that he counteract North Korea with decisive applications of force.

The outcome, though bloody and unpleasant for all sides, would not be in doubt. Nor would the balance of that blood and misery.

Let us hope China wakes up and the diplomats succeed.