In the Western Pacific, aircraft carrier strike groups may be the most obvious symbol of U.S. military power, and the reason why China is now working on its third aircraft carrier. But U.S. military leaders consider submarines to be its most important advantage against the great power challenge posed by China, a strategic threat emphasized in the Trump administration’s new National Security Strategy and National Defense Strategy. Because of the importance the United States places on its undersea advantage, one of the most important arenas of intensifying competition between China and the United States is also the least obvious — in marine laboratories and on oceanographic research and hydrographic survey vessels.

Since this work is often conducted by civilians, and almost as often has some dual-use application, it lacks the drama of a traditional arms race. But without mastery of the western Pacific’s oceanography, neither side can assert dominance over the undersea domain — granting freedom of action to its submarines, and denying it to adversaries.

A Look at the Numbers

While the United States fields a fleet of nearly 50 advanced, stealthy nuclear-powered attack submarines, China is increasingly asserting itself underwater. According to the U.S. Department of Defense, China currently has five nuclear attack submarines and 54 diesel submarines, and its fleet may grow to nearly 80 submarines by 2020. Chinese submarines reportedly penetrated rings of escorting destroyers and closely shadowed U.S. aircraft carriers operating in the western Pacific in both 2006 and 2015. In January of this year, a Chinese nuclear attack submarine sailed through the contiguous zone of the disputed Senkaku islands in the East China Sea, which Japan administers but that China claims as its own. Japan viewed the submarine’s transit as a serious provocation and escalation of the dispute.

The United States recognizes the challenge posed by China’s growing undersea fleet, but faces challenges to maintaining its own. In its most recent force structure analysis, the U.S. Navy said that it needs 66 attack submarines — nearly 40 percent more than it has today. Instead, it’s likely that the U.S. submarine fleet will actually shrink over the next decade. Shipyard constraints and the challenges of quickly expanding the skilled workforce needed to build submarines means that new construction probably will not be able to keep pace with the number of hulls that will have to be retired in coming years, let alone increase the fleet’s end-strength. As it is, the head of all U.S. forces in the Pacific has told Congress that the Navy can only meet half of his current peacetime requirements for submarine missions.

However, the contest for undersea dominance in the western Pacific is about far more than who has the most submarines, or even whose submarines are the most advanced. In the undersea domain, each side is listening for the other, either passively, for the sound a ship or submarine emits organically, or actively, by sending sound waves out and listening for them to bounce back off an adversary’s hull. Changes in water temperature, pressure and salinity affects how sound travels through it, so detecting and tracking an adversary while staying safely undetected oneself requires detailed understanding of the ocean depths, acoustics and the geography of the ocean floor.

In the United States, specialized centers leverage oceanographic science to provide operational advantages to its anti-submarine forces. To supply these centers’ need for oceanographic data the United States maintains a fleet of military-operated research and survey vessels, and partners with civilian scientific and oceanographic agencies, as well as private research institutions. The U.S. Navy’s oceanographic research activity received unexpected public focus a year ago when a Chinese naval vessel seized an unmanned data-collecting underwater glider in the South China Sea from the civilian- crewed research ship that was retrieving it.

Even if the United States will be challenged to maintain or grow its submarine fleet in coming years, that oceanographic data is critical to enabling recent initiatives to qualitatively improve its anti-submarine capabilities like upgrading Cold War-era submarine listening nets and researching a new generation of unmanned underwater vehicles that can be deployed from submarines to increase the ranges that they can detect, track and then engage adversaries from. Another customer for that data is the United States’ fleet of five civilian-crewed ocean surveillance ships that use sensitive sonar arrays to detect and track submarines ultra-long ranges. Demand for these ships’ services is so high that the Navy’s force structure analysis calls for building two more.

By contrast, last year the U.S. Department of Defense assessed that China still lacked a robust deep- water anti-submarine capability in its 2017 report on Chinese military developments, but noted it was progressing. One of the fastest-growing parts of China’s surface fleet are corvettes optimized for anti-submarine warfare, and a new long-range submarine tracking ship strikingly similar to the U.S. Navy’s ocean surveillance ships that appeared to be under construction last year now appears to be operational.

Mirroring its expanding undersea capabilities are increasingly advanced oceanographic projects and research with unambiguous military application. China recently launched a brand-new research vessel, one of 10 planned over the next decade. Under the auspices of civilian research, it has surveyed strategic waterways that control access to the South China Sea without necessary permission from the Philippine government. China has planned or completed a variety of oceanographic data networks in the South and East China Seas comprised of sensors mounted on the seabed, buoys, unmanned vehicles, submersibles and research vessels to collect data that can then be fused into comprehensive oceanographic models.

The military balance between China and the United States will rest largely on which is best able to exploit the ocean depths, and on that balance may rest the prospects for deterring a future clash from escalating into a more serious conflict. In that competition, scientists matter as much as submarines. China’s seizure of that U.S. Navy oceanographic glider in late 2016 illustrates how their competing research may provide fodder for future incidents. Last summer U.S. Navy reconnaissance planes closely watched Chinese experiments near the Caroline Islands that were reportedly part of China’s efforts to breach the so-called second island chain. As China’s expeditions push further into the western Pacific they are likely to draw ever closer scrutiny from the United States and opening another arena of strategic competition and source of tensions between them.

Steven Stashwick is a writer and analyst based in New York City. He spent 10 years on active duty as a U.S. naval officer with multiple deployments to the Western Pacific. He writes about maritime and security affairs in East Asia and serves in the U.S. Navy Reserve. The views expressed are his own. 

The views expressed in this post reflect those of the author and not that of the EastWest Institute.

"USS Carl Vinson (CVN 70) transits the So" (CC BY 2.0) by Official U.S. Navy Imagery