And, of course, North Korea shares a long, distended frontier with China and Russia. That’s a frontier that must be sealed to isolate the battleground, yet can’t be sealed by naval aviation. The border can only be sealed by Beijing and Moscow—dubious partners at best in the Korean standoff. That grants Pyongyang an opportunity for mischief-making. In short, it will be hard to crush North Korea’s armed forces, even if Washington orders a joint offensive.

And lastly, to swerve back to purely saltwater campaigns, there’s the least violent option: a full-bore naval blockade of the peninsula. Enforced with vigor and sufficient assets, a blockade would deprive North Korea of imported fuel, foodstuffs, and other commodities the beleaguered country must have to survive and fight. It would also balk Pyongyang’s efforts to export weapons, the makings of weapons, and bomb-making expertise to earn hard currency.

Corbett observes that a navy can apply pressure on a foe’s “national life” from day one of a conflict. Over time, he writes, it could exhaust that foe gradually—laying him low. But again, naval forces can only perform their blocking function at sea. They have little way to obstruct overland transit across North Korea’s northern border unless Washington wants to risk tangling with Chinese or Russian forces, and escalating a local conflagration to great-power war. Few relish that prospect. It’s a safe bet, then, that any blockade would leak to one degree or another.

For such reasons Corbett and Wylie caution that purely naval action seldom wins wars; Wylie verges on saying they never win wars. Only groundpounders can. To quote T. R. Fehrenbach’s classic history of the Korean War:

You may fly over a nation forever, you may bomb it, atomize it, pulverize it and wipe it clean of life. But if you desire to defend it, if you desire to protect it, if you desire to keep it for civilization, you must do this on the ground the way the Roman legions did: by putting your young men in the mud.

As it was in the 1950s, so it is now. Sea power furnishes the Trump administration military options in its confrontation with North Korea, but none of them promises easy, quick, or painless results. Thankfully, this is not lost on high-ranking defense officials. Secretary of Defense Jim Mattis, to name one, is reportedly a fan of Fehrenbach’s treatise. Indeed, General Mattis recently quoted him while holding forth on how a second Korean War would unfold. That’s good. It betokens strategic sobriety and humility—virtues any commander should cultivate.

The greats of strategy are smiling.

James Holmes is the inaugural holder of the J. C. Wylie Chair of Maritime Strategy at the Naval War College