The Commandant of the USMC has discussed this recently. In a conflict with China, don't defend fixed positions in the Western Pacific. This is a liner approach to war. Instead Marines would use a defense-in-depth, while naval surface and subsurface vessels lurked around the straights that block access into and out of the South China Sea (and outside of China's area anti-denial bubble).


The US Military Needs To Avoid A Linear Approach In A War With China

Earlier this month War on the Rocks carried an interview with General David Berger, commandant of the U.S. Marine Corps. The interview was mostly about personnel policy, but toward the end the interlocutors dwelt briefly on strategy and operations in the Western Pacific. Asked about the danger to fixed U.S. bases from Chinese missile salvoes, the commandant seemed to downplay fixed facilities and defenses as a warfighting implement.

Instead, said Berger, it’s imperative to “prevent the linear approach, like their wall against our wall, first island chain against what they have in mainland China—that sort of linear facing off at each other. Okay, that’s definitely not a healthy approach.” In other words, he believes emplacing marine garrisons all along the first island chain in more or less static positions would court defeat at the hands of People’s Liberation Army (PLA) rocketeers, who have at their disposal an imposing array of ballistic missiles boasting various ranges.


And Berger may well be right. Think about it in mathematical terms. A defensive perimeter is a line, and a line is made up of infinitely many points in continuous series. It’s tough to be stronger than a foe at infinitely many points on the map, all the time. An opponent intent on a breakthrough will simply mass forces at some point along the line and puncture it. That’s why military sage Carl von Clausewitz disparages long defensive lines, or cordons. “Lines,” he maintains, “constitute the most ruinous form of cordon-warfare. The obstacle they offer the attacker is worthless without powerful fire to support it. Otherwise it is good for nothing.”


Adds Clausewitz, defensive lines will “have to be very short and thus cover very little of the country, or the army will not be able to defend all points effectively.” To repulse an attempted breakthrough, commanders must be able to supplement ground forces holding the line with firepower delivered at a distance, at any point along the ramparts. How distended a perimeter defenders can hold, then, is a function of geographic distance, terrain, and the reach and volume of precision fire support available to marines, the navy’s fleet, and supporting air forces. It’s worth applying these Clausewitzian metrics to the problem of defending the first island chain from a PLA breakout, and confining the PLA Navy and Air Force to the China seas in the bargain.


A long-dead Prussian can help define the limits of the possible.
Read the rest of the article at the link.