Building additional 20 054As when you already have 30 of them in service is puzzling. It's even more puzzling when you consider that 054A is hardly at cutting-edge now and when you already have started building your next-generation frigate,
Unless, of course, situations or realistic scenarios call for a large and quick build-up. What are the situations that justify such a buildup? I can think of two, not necessarily mutually exclusive.
The first one is to anticipate some serious conflicts in the near future with very large and powerful adversaries, in which case you need the right class of ships to scale quickly and cost-effectively, to the quantity above and beyond what you need for normal time. The ship needs to be mature and capable. Among PLAN's surface combatants, 054A is that ship. It meets the criteria and strikes the balance.
The second is that I predict China will fight a war of presence in its surrounding waters (SCS/around Taiwan/ECS) and in the Western Pacific up to second island chain in the next decade. The Western Pacific has become very crowded waters with so many navies, both from neighboring and far-flung countries, sending their warships either to do FONS or joint exercises. PLAN needs many ships to track, monitor, repulse, control or simply be present everywhere and at anytime. Or better yet it may want to crowd out the adversaries' presence. For that, you need a lot of ships that can be deployed widely, cost-effectively and able to defend themselves.
There have been precedent for the second situation. Over 10 years ago, when Japanese government took over the ownership of Senkaku Islands, China launched a large and quick buildup of its CMS fleet by building more and much larger ships than its Japanese counterpart, and challenged this Japanese sovereign act by sending maritime coast guard ships regularly within the territorial waters of Senkaku Islands. Japan couldn't do anything about it and had to accept the constant presence of CMS ships.
Some recent news also help support this hypothesis.
In the first one,
, between Yonaguni Island of Japan and northeast Taiwan according to Japanese sources. It's a PLAN Type 054A frigate. This is something new. Expect more ships in more places regularly around Taiwan and SCS. In fact, I expect China will eventually have large naval presence to the east of Taiwan regularly if not constantly, including aircraft carrier group.
In the second one,
. Like the ECS ADIZ announced in 2013, this one will be difficult to enforce initially, but it is to lay the foundation for more enforcement in the future.
These are not isolated events. China has a strategy, clearly.