The past two decades have seen the People’s Liberation Army (PLA) as the Chinese military is known, undergo significant modernization programs. While these programs have primarily focused on land-based assets, they have begun to improve aviation assets as well. More recently, the naval arm of the PLA (the PLAN) has begun a serious campaign of upgrade and expansion. For a nation primarily concerned with projecting power into the sea—specifically the South and East China Seas—this is a necessary step. For those nations interested in countering these advances, these programs are quite alarming.

While most of the focus of the PLAN’s growth has been on its surface fleet, which now exceeds the U.S. fleet in number of ships by 370 to 299, with that number expected to grow further, less attention has been paid to undersea advances. In both type and quantity, the PLAN has begun to improve its submarine fleet while also making it more difficult for U.S. ships and submarines to operate. This expansion represents a threat to the U.S. Navy in three distinct and interrelated ways: it increases the danger posed to U.S. ships, makes it far more challenging for U.S. subs to carry out their roles in a potential conflict, and it spreads the already thin resources of the U.S. Navy even further.

In order to assess how the PLAN's subsurface community is stepping up the pressure on the U.S. Navy, it is illustrative to look at the specific advances that it is taking. These are, namely: new submarine designs in all classes, improved production capacity and a “Great Underwater Wall” and improved listening for surface vessels

An overview of new submarines

Two years ago, reports emerged that China had fielded a new fast attack submarine, a variant of the Type 039 Yuan class. This C variant features a distinctive sail shape, reducing its acoustic signatures by several decibels. Potentially more significant, however, is the fact that it became operational only a year or so after launching, which is unusually fast for a new class of submarine. In addition to the new Yuan variant, China has just fielded the Type 095 and is working on the Type 096, ballistic missile submarines. While these are still in their infancy—relatively speaking—they represent important steps forward. Experts believe they will be as quiet as the Russian Akula-class. Furthermore, they are larger than current Chinese missile subs; the Type 095 has sixteen vertical launch tubes and the Type 096 is expected to have twenty-four. Miniaturization programs have shrunk the size of Chinese submarine-launched missiles meaning the new subs won’t have quite as large of a “turtle back” as seen on the Type 094 which will yield a marked increase in performance.

Currently, the United States and China have near parity in terms of their number of submarines. This number is forecasted to rapidly shift, however, as the PLAN ramps up its production. As evidenced by the new Type 039C, it is already adept at quickly getting subs from the yards to the fleet. Expansions in a major yard in Wuhan mean China will be able to pump out subs at a rate the United States and other nations will most likely be unable to match.

Great Underwater Wall

For nearly a decade, the PLAN has been working to reduce one of its major vulnerabilities, namely its difficulties detecting U.S. subs in the South China Sea. To accomplish this, it is setting up underwater hydrophones similar to the Sound Surveillance System (SOSUS) used by the United States and allies to track Soviet subs moving through the Greenland-Iceland-UK (GIUK) gap. In addition to stationary sensors, the PLAN has integrated towed sonar arrays on many of its vessels as well as expanding its fleet of sub-hunting aircraft. Furthermore, it has worked to integrate these platforms so they can more easily tap into existing hydrophone networks and share information.

Challenges to the U.S. Navy

The Type 095/096 ballistic missile subs are both capable of carrying the YJ-18 anti-ship missile. Modern naval engagements will most likely feature salvos of missiles fired from beyond the horizon by multiple types of platforms. Massed fires will be key to overwhelming enemy defenses and achieving victory. Having subs nearby with large quantities of ship-killing missiles adds more weight to any PLAN barrage while increasing the survivability of the launch assets.

In addition, a rapid increase in Type 039 production would allow the PLAN to allocate some of those subs to attack surface vessels. Subs represent a major threat to surface ships and fleets must expend resources defending against that threat which could potentially make them vulnerable elsewhere. All this makes the South China Sea even less survivable for surface assets.

Challenges to the U.S. Navy: Reduced Submarine Effectiveness

Although U.S. subs are generally very quiet and difficult to track, with the above improvements the PLAN now has several counters. One of the biggest difficulties in hunting submarines is finding them after they have left their port and are in the open ocean. The “Great Underwater Wall” would give the PLAN an indication of when a U.S. sub has begun operating in the South China Sea and allow it to vector assets to track that sub. Given that a U.S. response to an invasion of Taiwan would likely feature U.S. attack subs trying to sink Chinese ships in the Strait of Taiwan, finding these subs is a top priority for the PLAN.

Once the PLAN has located the subs, it can use its much larger fleet of attack boats to hound them. Its greater numbers and improved capabilities as well as knowledge of where the U.S. boats are coming from should make them effective enough to prevent the U.S. boats from completing their missions.

Challenges to the U.S. Navy: Resource Spreading

Recently, China has begun to maintain at least one ballistic missile sub on patrol at all times. PLAN ballistic missile ranges mean these boats can loiter in the South China Sea and still hit targets on the continental United States. The U.S. Navy is thus very interested in keeping track of these submarines. Normally, this can be accomplished by fast attack submarines or patrol aircraft and helicopters. Given the difficulties mentioned above, U.S. submarines may be virtually barred from operating in the South China Sea, meaning air assets will have to carry the load. These aircraft require air superiority to conduct their mission, which requires more resources. Carrier Strike Groups may be unable to provide these resources as they are fending off missile attacks from Type 95/96s or conventional torpedo runs carried out by Type 039Cs.

As the PLAN continues to develop its subsurface assets, the risks posed to the United States will only increase. Their interconnected nature means countering one may make you vulnerable to another—the foundation of combined arms. As tensions with China grow, planners must consider these challenges and how best to confront the growing submarine fleet of the PLAN.

About the Author: Maya Carlin

Maya Carlin, National Security Writer with The National Interest, is an analyst with the Center for Security Policy and a former Anna Sobol Levy Fellow at IDC Herzliya in Israel. She has by-lines in many publications, including The National Interest, Jerusalem Post, and Times of Israel. You can follow her on Twitter: @MayaCarlin.