The Japan Maritime Self Defence Force (JMSDF) and South Korea's Republic of Korea Navy (ROKN) both operate modern flat-topped aviation platforms, although none of them are currently classified as aircraft carriers.
These warships are: the destroyers (helicopter) Izumo, and Kaga, of the JMSDF, and the landing platforms (helicopter) (LPH) Dokdo, and its very recently completed sister ship, Marado, of the ROKN.
Recent reports by the Japanese Asahi Shimbun website, and South Korea's Yonhup news agency, have indicated that both nations are currently assessing the feasibility of upgrading these ships to operate advanced F-35B Lightning II short take off and vertical landing (STOVL) fighter bombers.
The catalysts for this development are likely to be concerns over the ever-increasing assertiveness of China over Asia's seaways, and offshore islands, as well as the current regional tensions over North Korea
The four vessels' flight decks are long enough to operate the F-35B, and according to some reports, the aircraft lifts on the Japanese vessels are already sufficiently large to accommodate the F-35B. All the ships, though, would need to be fitted with ski-jump aircraft launching aids.
Also required would be the application to their flight decks of thermal-resistant coating, in order for the decks to withstand the extremely high temperatures generated by the F-35B's lift engine, as well as enhanced air traffic control facilities, and, probably, some modifications to the hangars.
Both countries are already receiving deliveries of F-35s but they are the F-35A version, which lacks a dedicated lift engine, and is designed to operate from shore airfields.
Therefore, additional STOVL examples will have to be purchased, unless the main intent is actually to provide extra, dedicated support for regional maritime operations by US Marine Corps F-35Bs, which were recently deployed to Japan, and are now operating from the US Navy LPH Wasp, as well as Iwakuni air base.
Whatever Seoul's and Tokyo's ultimate intentions might be, it is certain that operating the stealthy, and very heavily armed, F-35B at sea will certainly substantially boost JMSDF and ROKN offshore combat capabilities.