The following article is part of our cross-posting partnership with Information Dissemination’s Jon Solomon. It is republished here with the author’s permission. Read it in its original form here.

By Jon Solomon

There was a pretty lively debate in the comments to Chris Mclachlan’s post last month about the Combat Logistics Force. No one took issue with his observations that the CLF might be undersized for sustaining high-tempo forward U.S. Navy operations in the event of a major Sino-American war. Nor did anyone contest his argument that our replenishment ships lack the basic self-defense capabilities their Cold War-era predecessors carried. Instead, the debate focused on Chris’s assertion that CLF ships ought to be escorted during wartime by a small trans-oceanic surface combatant possessing medium-range anti-air and anti-submarine capabilities.

Needless to say, I agree with Chris’s view. Such an escort would be a necessary part of the overall combined arms solution set to protecting not only CLF assets but also the shipping that would surge reinforcements and materiel to embattled U.S. allies in East Asia, provide steady logistical sustainment to the U.S. and allied forces deployed to or based in those countries, and maintain the flow of vital maritime commerce to and from those countries. One rarely sees any of these four critical tasks acknowledged in discussions within the security studies community. I believe that represents a dangerous analytical oversight, as an American failure to adequately protect its own and its allies’ sea lines of communications in a war with China would be strategically disastrous. In today’s post, I’m going to outline China’s ability to threaten these lines in a notional major war. On Thursday, I’ll outline how the U.S. and its allies might offset that threat.

Let’s first look at the strategic geography of the problem. The sea lanes in question pass through the waters between the First Island Chain and the line stretching from Hokkaido through the Bonins and Marianas to the Palaus (e.g,  the “Second Island Chain”). I’ve recently written about the PLAAF’s effective reach into the Western Pacific, and it’s been widely understood for years that late-generation PLAN submarines possess the technological capability to operate for several weeks in these waters before having to return to port. China would be hard-pressed to achieve localized sea control anywhere within this broad area; its own surface combatants and shipping would be just as vulnerable to attack. It wouldn’t need sea control, though, to achieve its probable campaign-level objectives of bogging down (or outright thwarting) an effective U.S. military response, or perhaps inflicting coercive economic pain upon one or more embattled American allies. The use of PLA submarines and strike aircraft to pressure U.S. and allied sea lines of communications would be entirely sufficient. And as Toshi Yoshihara and Martin Murphy point out in their article in the Summer ‘15Naval War College Review, these kinds of PLA operations would be consistent with the Mao-derived maritime strategic theory of “sabotage warfare at sea,” albeit at a much greater distance from China’s shores than the theory originally conceived. Such operations have been widely discussed in Chinese strategic literature over the past two decades.[i]

It bears noting that our East Asian treaty allies like Japan, South Korea, and the Philippines would have inherent roles and responsibilities defending their sea lines of communication. Nevertheless, they probably would not be able to fulfill the mission entirely on their own given their maritime forces’ sizes and capabilities. There would probably need to be a geographical line of responsibility similar to what the U.S. and Great Britain worked out in the Atlantic during the Second World War; shipping protection west of the line would primarily be the ally’s responsibility, and the U.S. would be primarily responsible for shipping protection east of the line. Even so, the U.S. would probably still need to contribute escorts and supporting forces to assist the ally in protecting sea lanes that were within some threshold distance of the Chinese mainland. Shipping protection in the approaches to the Ryukyus, Taiwan, or western Luzon particularly come to mind.

While it is true that U.S. and allied forces could probably pressure the PLA’s ability to push submarines and aircraft through the Ryukyus’ various straits or the Luzon Strait in a war, they would probably not be able to fully seal those doors—at least not during the conflict’s early phases. The biggest reason for this would be the straits’ sheer proximity to the Chinese mainland: PLAAF/PLAN fighters would be readily able to escort their strike aircraft brethren out into the Western Pacific and back, not to mention threaten any U.S. or allied anti-submarine aircraft or surface combatants patrolling the straits. Granted, Chinese fighters would be exposed to any sea-based and mobile land-based area air defense systems covering the straits and their approaches. They might also be confronted by U.S. or allied fighters operating from austere island bases in the vicinity of the straits, or from aircraft carriers or land bases located at various distances “over the horizon” to the east. U.S. and allied defenders could additionally use any number of countertargeting tactics to reduce their susceptibility to attack.

However, even if the PLA could not damage or destroy many of these forces per raid, it could still take actions that effectively suppressed the straits “guardians.” One tactic might be to salvo land-attack or anti-radar missiles to distract the defenders or induce them to keep their “heads down” shortly before or during a straits transit. Another might be to damage runways or austere airstrips as possible in order to constrain the defenders’ air operations; repairs could take precious hours. Electronic attacks and tactical deception could also be used to screen transiting PLA aircraft and submarines. Periodic PLA suppression raids would neither be small undertakings nor without risk to the forces performing them, but they might be sustainable on an as-needed operational tempo for several weeks or months at minimum.

The other factor that would make it impossible to hermetically seal the First Island Chain barrier would be the difficulty in maintaining persistent U.S. or allied submarine coverage in all of the requisite straits. The U.S. presently has thirty-one non-special-purpose SSNs stationed in the Pacific; three are homeported in Guam and twenty in Pearl Harbor. Only a small number would be deployed at sea within quick steaming of the straits, though, unless timely indications and warning of an impending crisis or conflict were received and then acted upon by U.S. leaders. The high-readiness Guam boats would be able to arrive on scene fairly rapidly once sortied, but it would take several more days for them to be reinforced by Pearl Harbor boats—not all of which might be immediately surgeable due to inter-deployment maintenance. Japan could surely contribute a number of its sixteen modern SSs in active service, but again not all of them might be surge-ready at any given time. And while the U.S. and Japanese fleets will be receiving additional boats over the coming decade, it will not be at a rate and scale that would dramatically change the straits coverage math. Hypothetical seabed-mounted sonar arrays in these straits or their approaches might help improve these odds by cueing available U.S. or allied submarines (or other anti-submarine forces) to a PLA submarine transit. The probability of a friendly submarine intercepting a PLA submarine detected this way, though, would depend upon the time between when the cue was broadcast and when it was received by the friendly sub, how the friendly sub’s effective sonar ranges in those waters affected its ability to redetect the trespasser, and whether the friendly sub could cover the distance from its starting point to have a chance at redetection before the cueing data “aged out.” More than one boat might be required to cover any particular strait with a certain margin of confidence; this would be especially true for the wider straits. Nor would anti-submarine patrols in the straits be the two sub fleets’ sole mission at the beginning of a major war: there would be equal if not greater demands for land-attack strikes, anti-submarine and anti-surface patrols inside the First Island Chain, anti-submarine patrols between the two island chain lines, special forces insertion/extraction, and far-forward intelligence/surveillance/reconnaissance. U.S. and Japanese submarine coverage of the straits simply could not be absolute.

It would be excellent if U.S. and allied forces could attrite the PLA forces making or supporting straits transits by a few percent each time without suffering equivalent attrition; the cumulative effects on the PLA’s overall warmaking capacity would be significant. But it would take weeks if not months for those effects to really show. That’s why the ability to logistically sustain the land-based forces waging the protracted frontline fight would be so crucial to U.S. war strategy. If the PLA were to inflict enough pressure on these logistical flows, the barrier defense would eventually wither on the vine.

It’s also important to remember that this imperfect barrier would only function in an open war—not during a crisis. Any PLAN submarines sortied prior to the outbreak of open hostilities could in theory patrol between the two island chain lines for campaign-significant amounts of time before having to hazard a trip back through the First Island Chain gauntlet. Modern PLAN SSNs like the Type 093 and its Type 095 follow-on would have an obvious endurance advantage over Air-Independent Propulsion (AIP) boats like the Type 041, but even the latter could probably remain underway for a few weeks before requiring a return to port. During that time, the mere fact that PLAN submarines were unlocated in the Western Pacific would undoubtedly affect U.S. operations (and tempo) in theater. The Royal Navy’s experience coping with a single unlocated Argentine submarine during the Falklands War is instructive on that point.

It would not take many PLAN submarines to generate such effects. For instance, let’s assume that the PLAN allocated its Type 041s, Type 093s, and Type 095s for war-opening operations between the two island chain lines while simultaneously holding its Type 035A/B/G, Type 039, and Kilo-class diesel-electric boats back for operations within the East and South China Seas. Let’s also assume China had its planned twenty Type 041s and five Type 093s in commission, plus perhaps five Type 095s as well, when a conflict erupted. Lastly, let’s assume that these boats’ material conditions of readiness were high enough to sortie two-thirds of them into the Western Pacific as the crisis phase peaked. Thirteen AIP boats and six SSNs might not seem like a lot within such a broad expanse. However, as Julian Corbett pointed out a century ago, the most “fertile” areas for hunting ships are “the terminals of departure and destination where trade tends to be crowded, and in a secondary degree the focal points where, owing to the conformation of the land, trade tends to converge.”[ii] If the PLAN followed Corbett’s logic, it might position its submarines in waters the U.S. and its allies would have to traverse to access (or break out of) selected major ports along the First Island Chain during the war’s first weeks. Or it might assign those duties to the Type 041s and deploy its SSNs in the waters just west of the Marianas that shipping from Guam, Hawaii, or the continental U.S. might seek to traverse. Or if the Chinese Ocean Surveillance System’s (COSS) coverage between the island chain lines remained adequate after the war started, China might try to steer its SSNs into mid-transit contact with U.S. or allied shipping.[iii] What’s more, the lingering effects of a PLA conventional first strike against major U.S. and Japanese bases in the Japanese home islands and Okinawa, subsequent PLA suppression operations against U.S. or allied straits-guarding forces along the Ryukyus-Luzon line, and in-theater U.S. and allied anti-submarine-capable forces’ sheer combat load prior to the arrival of reinforcements from the U.S. suggest that at least some PLAN submarines could complete at least one full cycle from their patrol areas to port for replenishment and then back into the Western Pacific before the “happy time” window began to close. This would especially be true for PLAN submarines patrolling the approaches to the Ryukyus, Taiwan, or Luzon.

Add the PLAAF/PLAN strike aircraft threat back into the mix and it should be apparent that U.S. and allied use of the Western Pacific’s surface between the two island chain lines would likely be opposed early in a notional war. The key variables driving China’s anti-shipping potential within these waters would be COSS’s ability to provide PLA aircraft and submarines with actionable targeting cues despite intense U.S. (and possibly allied) efforts to degrade and deceive this system-of-systems, the PLA’s ability to push those forces through contested First Island Chain straits when and where needed, and the operational range and endurance of those forces.

Jon Solomon is a Senior Systems and Technology Analyst at Systems Planning and Analysis, Inc. in Alexandria, VA. He can be reached at [email protected]. The views expressed herein are solely those of the author and are presented in his personal capacity on his own initiative. They do not reflect the official positions of Systems Planning and Analysis, Inc. and to the author’s knowledge do not reflect the policies or positions of the U.S. Department of Defense, any U.S. armed service, or any other U.S. Government agency. These views have not been coordinated with, and are not offered in the interest of, Systems Planning and Analysis, Inc. or any of its customers.

Featured Image: QINGDAO, CHINA – JULY 02: (CHINA OUT) CNS Harbin DDG-112 frigate fires a missile during live-fire drill on Yellow Sea on July 2, 2015 in Qingdao, Shandong Province of China. Naval vessels and soldiers mainly from China people’s Liberation Army Navy North Sea Fleet and part of soldiers of China people’s Liberation Army Navy East Sea Fleet, the Second Artillery Force of the PLA, Chinese PLA Shenyang Military Region and Chinese PLA Jinan Military Region attended the live-fire drill on Yellow Sea on Thursday. (Photo by VCG/VCG via Getty Images)