Here's What You Need to Know: The distinction between helicopter carriers and aircraft carriers remains dubious. 

Meet the Izumo—the Japanese Maritime Self Defense Force’s largest ship, displacing a gargantuan twenty-seven thousand tons. The vessel’s lengthy, flat deck measures the length of two-and-a-half football fields at 248-meters. The Izumo typically hosts seven SH-60K helicopters designed to comb the seas for hostile submarines, plus another two search-and-rescue models—though it can carry as many as twenty-eight choppers if necessary. The Izumo also has several elevators to lower the helicopters to an internal hangar deck.

But by no means call the Izumo an aircraft carrier. She, and her sister ship the Kaga, commissioned in 2017, are “helicopter destroyers.”

This distinction is especially dubious because unlike the predecessor of the Izumo-class, the Hyūga-class, which was armed with torpedoes and medium-range anti-aircraft and anti-submarine missiles, the Izumo does not carry any longer-range weapon systems to perform regular “destroyer” roles. Its only armament is a couple of short-range Phalanx and SeaRAM self-defense systems designed to shoot down incoming missiles seconds before they impact.

Yet the distinction remains because—at least until recently—the consensus in Tokyo was that “carriers” are offensive weapon systems, and offensive weapons are forbidden to Japan’s Self-Defense Forces by Article 9 of its constitution.

Though the distinction between “offensive” and “defensive” weapon systems is arguably a bit arbitrary—aggressive powers still need to defend themselves, defensive powers may want offensive weapons for deterrence or counterattack—there’s no denying that carriers can and have been used as floating airbases to wage offensive wars on foreign countries.

Japan, in fact, is the original pioneer of carrier warfare. At the beginning of World War I, a Japanese cruiser lowered ship-based floatplanes into the water to fly the first naval air strike in history against a German cruiser. (The British Royal Navy, however, was the first to combat deploy a carrier with a flight deck for the Tondern raid in 1918.) The Imperial Japanese Navy went on to develop a large carrier arm during the 1920s and 1930s and used them to deliver the devastating surprise attack that knocked out American battleships at Pearl Harbor on December 7, 1941. That formidable force only met its first major defeat battling U.S. Navy flat-tops in the Battle of Midway, and then its pilots and fleet carriers bled away in a series of costly engagements between 1942 and 1944.

However, carriers aren’t confined to offensive roles. They can deploy fighters to protect friendly surface ships and bases from attack, or dispatch patrol planes and helicopters to scout out the position of hostile ships and submarines. The Japanese military is particularly concerned with its ability to defend distant islands on the southwestern end of its archipelago such as the disputed Senkaku  Islands (called the Diaoyu by China) and the Ryuku Islands, which include Okinawa. These islands are hundreds of miles away from the central Japanese home islands, complicating efforts to defend them by air or take them back from invaders.

Of course, while helicopter carriers are highly effective at hunting submarines—and as such are essentially defensive in nature—they aren’t useful for providing air cover or ground support. But it just so happens that Japanese ship designers discretely designed the Izumo-class to be capable of supporting jump jets, which can lift off over very short distances, or even vertically like a helicopter.

Japan doesn’t currently have any jump jets—but reports indicate it is actively looking into acquiring a highly capable type. The U.S. Marine Corps operates an F-35B Lightning II jump jet model designed to fly from small amphibious carriers—a type that saw its first combat test in Afghanistan on September 27, 2018. Japan hasn’t bought any F-35Bs yet, but it is license-building forty-two conventional F-35As.

The F-35 boasts excellent stealth characteristics and computers but is a bit inferior in terms of traditional flight performance parameters (speed and maneuverability) when compared to fourth-generation fighters. However, the F-35B has a far superior performance to preceding jump jets like the Harrier and Yak-38. Though slower than a traditional air superiority interceptor, the Lightning’s powerful sensors and low-observable characteristics would make it a very sneaky stalker of otherwise faster and more maneuverable adversaries. This means the F-35 is able to pick off enemy aircraft with long-range missiles and then dart away before being detected.

Already, in May 2018, Tokyo released portions of a study concluding the Izumo and Kaga could be used to carry U.S. Marine jets assisting in the defense of Japanese soil. Earlier, however, a Japanese newspaper revealed that the government of Shinzo Abe has drawn up plans to—and evaluated the substantial cost of—acquiring as many as forty F-35Bs for the Japanese Air Self Defense force to replace aging F-15Js. Although F-35Bs are appealing because their lift fans would allow them to operate from the shorter civilian airfields of remote Japanese islands, Tokyo has also studied the cost of modifying the Izumo-class carriers to accommodate up to ten of them at a time.

Such modifications would entail heat-resistant paint to the decks, as an F-35B’s vertical lift fans generate such intense heat they could threaten to damage the deck! However, some sources claim that the decks were treated with such paint early on—giving an idea of how the designers of the Izumo-class were thinking well ahead of the possibility of transforming “helicopter destroyer” into a full-fledged aircraft carrier. The Izumo-class, however, would also need to incorporate a ski-jump-style ramp to assist the Harrier in making short takeoff runs, as vertical takeoffs burns excessive fuel and still damage the deck excessively.

Yet overtly operating fixed-wing aircraft from carriers is a domestically sensitive matter to the pacifistically-inclined Japanese—as well as to Beijing. Though China has dramatically expanded its own carrier aviation capabilities in recent years—the PLA Navy has gone from zero to two mid-sized carriers in the last five years, and plans to phase in four more by the mid-2020s—Beijing has already complained about the Izumo-classes capabilities, arguing that Japanese carriers betray a warlike intent.

Undeniably, a return to Japanese carrier aviation would carry a historical association with Imperial Japan’s naval prowess—and ruthless deeds—prior to and during World War II. However, that doesn’t mean a couple ships carrying around a dozen jet fighters herald an aggressive foreign policy. Other countries like Brazil have operated carriers without using them in expansionist campaigns. For a wealthy island nation like Japan, operating a few carriers to help defend its far-flung islands and patrol its seas makes abundant sense.

However, the issue will remain emotionally fraught both in Japan and China—which explains why though the concept has clearly been mulled since the Izumo-class was first designed, discussion of the possibility has been veiled by terminology such as ‘helicopter destroyer.’ However, as Japan’s conservative ruling party pursues new records in defense spending to balance China’s expanding naval power, its interest in operating jump jets from carriers seems likely to increasingly go from implicit to explicit.

Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring.

This article first appeared in October 2018 and is being republished due to reader interest. 

Image: Creative Commons "File:JS Izumo (DDH-183) just after her launch.jpg" by Dragoner JP is licensed under CC BY-SA 3.0