The South Korean Navy has received a new 23,000 ton AOE II type combat support ship, the Soyang. This is the first new AOE (Fast Combat Support) ship for the navy since they received three 9,100 AOE I class ships in the 1990s. The AOE II, in addition to carrying more (11,000 tons) supplies (fuel, spare parts, food) than the older AOE I is also a bit faster (43 kilometers an hour) and has a crew of 140. The AOE II carries a helicopter and is armed with Phalanx CIWS (20mm autocannon that can destroy incoming missiles as well as nearby small boats or aircraft) as well as countermeasures and modern electronics. American is building more (and larger) AOEs because of the Chinese threat and the fact that South Korea now has a much larger navy than it did in the 1990s.
China has not been idle either. In 2017 China put its first AOE “Hulun Lake”, Type 901 fast replenishment ship into service. This was a big deal. Chinese Navy officials noted that this fast supply vessel would, as expected, enable the only Chinese aircraft carrier (Liaoning) to operate much farther from its base and for longer periods. Before the Type 901 AOE Liaoning and its escorts had not operated much farther than onboard fuel allowed. A second carrier, similar in design to the Liaoning, is nearly completed and expected to enter service by 2020 as are more Type 901s, with one more 901 already under construction.
The Type 901 is the largest (over 40,000 tons) replenishment ship China has produced and similar in size and capability to the twelve American T-AKE replenishment ships. The 40,000 ton T-AKEs service a much larger fleet than the Type 903s and Type 901s. The T-AKEs are part of a larger replenishment fleet required by American warships operating worldwide. But China has been expanding its replenishment ship force as it puts more warships into service and expects to eventually (by the 2030s) to rival the U.S. Navy worldwide.
The Type 901 has a top speed of 45 kilometers an hour (to keep up with a carrier task force) and room topside for two or more CIWS autocannon (similar to the American Phalanx) for anti-missile defense. At least one more Type 901 appears to be planned but the Chinese usually wait until a new ship type has a year or so at sea before more are ordered. The Type 901 seems more influenced by the four 48,000 ton T-AOE fast (45 kilometers an hour) supply ships the U.S. put into service during the mid-1990s. These are now being retired because the slower (37 kilometers an hour) T-AKEs and other supply ships got the job done more efficiently and cheaply. This is partly because the United States has access to more overseas ports for resupplying and refueling its carrier task forces.
South Korea does not have any carriers but it does have some large destroyers (up to 14,000 tons) that look like small carriers but carry only helicopters. South Korea will build more AOE II type ships is the first one performs as expected in actual service. For now the three AOE I ships can remain in service for another decade or more. But the AOE I is not suitable for operations far from South Korea while the AOE II is.
The South Korea Navy is almost entirely locally built and has expanded enormously since the 1990s. Currently, the fleet has 16 modern submarines (18 by 2019). All these subs entered service after 1992. There are twelve destroyers (the oldest one entered service in 1998) and more are under construction. There are 13 frigates, with the three oldest from the late 1980s. The 14 corvettes all date from 1989 and the early 1990s. There are also about fifty patrol boats with the 170 ton ones 1978-94 being replaced by new 570 ton ships (18 so far, the first arriving in 2008). There are also a dozen amphibious ships including two 18,000 ton LPHs (one in service the other will be in 2020.
The South Korean Navy was originally meant to be a coastal defense force, mainly because the main threat was from North Korea or nearby China. Since the late 1990s it became obvious that all those destroyers and frigates being built in South Korea performed well on the high seas the South Korea Navy was rapidly becoming one of the largest and most modern in East Asia. Together South Korea and Japan pose the greatest naval threat to China. Although the American fleet is much larger the portion of the U.S. Navy stationed in the West Pacific is smaller than the combined South Korean-Japanese force. The Americans have the large carriers, large amphibious ships and nuclear subs but the South Koreans and Japan have most of the subs (all diesel-electric), destroyers and frigates. South Korea already has three large (11,000 ton) Aegis equipped destroyers with three more under construction. Japan also has Aegis equipped destroyers and large destroyers that function as helicopter carriers.