One or more Chinese submarines would protect the Liaoning carrier group by helping to prevent an enemy submarine getting between the carrier and the carrier's surface escorts. The carrier group zone that a Chinese submarine protects can be called the "Box".
By using SSKs the amount of lead time may alert enemy submarines and other sensor platforms (eg. the Miyako Strait undersea array) that a carrier movement may be imminent. Use of SSNs for this long range lead-checking would have been preferable, but China has not had the time or the defence budget to develop sufficiently quiet SSNs or produce such SSNs in quantity. Chinese MPA (aircraft) and UUVs (in future) might also do lead-checking (also called "sanitising").
Still, a Chinese SSN or two within the Box may accompany the group. The noise of the surface ship engines may mask relative (to diesels and turbines) more quiet SSN nuclear engines.
As can be assumed from the youtube below the East China Sea, bordered by the Miyako Strait, is saturated with enemy sensors (including long range radars) and by weapons, including submarines and by anti-ship missiles and aircraft on island bases. In practice this saturation would preclude Chinese carrier movements in medium level warfare (shooting war) or high level (nuclear) warfare.
- Japanese (Oyashios and Soryus)
- US Los Angeles and Virginia SSNs
- South Korean Type 209s and 214s, and
- Taiwanese Hai Lung class
For the purposes of initial carrier group trials China is forced to use this "near seas" environment. Reasons include:
- this hostile submarine threat, and
- questions about the reliability of the Liaoning's propulsion (possible need to tow Liaoning at short
Also keeping Liaoning in the near seas is its inadequate protection from its airwing. Liaoning's airwing is still weak, with only 24 short range (due to ski jump launch) J-15 fighter aircraft. Liaoning therefore needs to operate under the "bastion" protection of aircraft and DF-21D anti-ship missiles on Chinese mainland and Hainan Island.
Long range Chinese airpower and SAMs on Woody Island and other South China Sea islands can also help protect Liaoning. Perhaps DF-21Ds and DF-26s will be based on South China Sea islands in future.
Like other Kuznetsov carrier derivatives Liaoning may utilise land (including island) air bases for its strike fighters to increase the fighter's range and weapons capacities. China's South China Sea island base building therefore has that extra value - not yet officially apparent. This is noting Russia's Kuznetsov has been sending its own fighters to land air bases in Syria.