Japan is slowly changing its security posture away from the minimalistic posture associated with the so-called “Yoshida line”. Post-war Japan has traditionally been preoccupied with economic recovery, eschewed great power status, and delegated nuclear retaliation to its US ally. On the contrary, and in light of a growingly tense regional environment where US security guarantees cannot be taken for granted, the Abe administration has aimed at overhauling Japan's security regime towards a more proactive role. More recently, Japan has scrapped the expensive Aegis Ashore missile defense system and is hinting at shifting towards the more active deployment of offensive capabilities. China is the main target of these initiatives.
How can China be deterred and what is deterrence? The academic Luis Simón posits that the debate on American efforts to deter China can be disentangled into a more offensive “punishment” strategy that allows states to strike an adversary's territory through long-range strike capabilities, and a more defensive “denial” approach that prioritizes the development of capabilities aimed at tailoring and limiting the damage of potential military threats. Japan's inability to match the pace of Chinese military modernization means that it is bound to rely on extended deterrence (provided by the US through the nuclear umbrella) along with closer alliance cooperation, based on promoting “jointness” and interoperability between the armed forces of Japan and the USA. Still, Japan's main deterrence strategy is premised on “denial,” because it aims at shoring up its asymmetric capabilities to make a Chinese invasion of the archipelago as costly as possible.
Japan's strategy now somehow reflects China's own Anti-Access Area Denial approach and is largely in line with Japan's traditional “defensive realist” stance that maximizes security for the purpose of homeland defense, while mitigating the regional security dilemma. And Japan's recalibration of its defenses towards its far-flung southwestern flank, along with the establishment of an amphibious rapid deployment brigade, the installation of new mid- and short-range surface-to-ship and surface-to-air missile units, deployment of ballistic missile defense systems (now especially at sea) and redoubled efforts in promoting anti-submarine warfare, all point at the prioritization of homeland defense and deterrence by denial.The United States had actively sponsored the development of its Asia-Pacific allies' denial capabilities to prevent China's regional dominance. Under the Trump administration, the US increased the number of freedom of navigation operations, while more actively enlisting the participation of likeminded partners in the deterrence mix, and deploying its military and coast guard vessels in East Asian waters. In order to reassure its allies, the US claimed it would retain the ability to “punish”, or defeat China, especially through strategic and, “if necessary,” tactical nuclear weapons.
Yet, Washington's escalation dominance traditionally also targeted and circumscribed Japan's maneuverability, but this was changing under Trump. According to a former US defense official quoted in the above-mentioned article by Luis Simón, “the ability for the US to 'concentrate on the offensive side of things' would mean that 'Japan would not have to do it itself,' and that 'would also be most welcome from the perspective of managing the Japan alliance adequately'.” After all, the Obama administration had objected to Abe's Japanese acquisition of strike capabilities. Instead, the advent of the Trump administration allowed for a change in US defense planners' calculus, one that provided incentives for Japanese rearmament beyond deterrence by denial. This was the end product of the new, more confrontational approach of the US government towards China, one that enlisted like-minded partners for its “big stick diplomacy” towards China, and was a manifestation of the US president's desire to boost American exports, including expensive arms sales.
In 2019, Japan procured power projection capabilities that would have allowed for a more offensive declination of deterrence, although capabilities were still limited. To be sure, Japanese armed forces remain politically constrained to strictly defensive functions: a deeply engrained antimilitarist and anti-nuclear ethos both prevented the acquisition of nuclear weapons and curtailed Abe's ability to make greater use of the military as a tool of statecraft. But the Abe administration had already relaxed the legal constrains previously limiting Japan's acquisition of offensive capabilities.During Trump's visit to Japan, in a historic first, Trump addressed military personnel along with Abe on top of the Kaga helicopter carrier that − as per the December 2018 Cabinet-approved NDPG − was now allowed to host aircrafts, such as expensive F-35Bs, a powerful stealth fighter. By 2030 Japan's F-35 fleet is poised to reach a total of 147, making Japan the largest foreign buyer of the Lockheed Martin-made jet and possibly tipping the balance of fifth-generation air power in Japan's favor – especially if the F-35s worked through a seamless alliance integration, allowing Japan to share US carriers. The Japan Maritime Self-Defense Force officially maintains that the two Izumo-class warships are “multipurpose destroyers,” but they are in fact aircraft carriers. As such, they endow Japan with mobile air defense platforms and a degree of power projection. This was a modest one, however, given the limited number and size of the carriers, China's sophisticated anti-ship missiles (from ground, air and sea), and the steep costs of procuring, operating and maintaining an aircraft carrier
The April 2019 US-Japan Security Consultative Committee led by the ministries responsible for foreign affairs and defense matters (also known as “2+2”) emphasized “cooperation to introduce advanced weapons systems to Japan and to further streamline the foreign military sales process”. Moreover, the 2+2 meeting also aimed to increase deterrence in the cyber domain, by stating that “a cyberattack could, in certain circumstances, constitute an armed attack for the purposes of Article 5”. This is a noteworthy development in alliance politics – one that went hand-in-hand with Japan's quest for offensive cyber capabilities that could be used for deterrence purposes during peacetime and defensive aims during an emergency. In 2019, Japan's Self-Defense Forces' cyberdefense unit had expanded from 150 to 220 personnel from the army, navy and air force, and reportedly “outsourced the development of offensive cyber capabilities to one or several unnamed private Japanese companies”.
Finally, the Abe administration and Japanese defense planners likely felt reassured by the US withdrawal from the Intermediate-Range Nuclear Forces (INF) Treaty. The withdrawal is nominally aimed at Russia's violation of the treaty, but China's development of nuclear and conventional missile capabilities is arguably a more pressing reason that hinted at a US-China missile race, prompting US overtures towards Japan's acquisition of conventional strike capabilities. In order to counter China's ballistic and ground-launched cruise missile capabilities, the United States government swiftly considered installing land-based intermediate-range missiles in China's proximity, Japan being a prime candidate for deployment.In 2019 the Abe administration signaled its intention to counter China's advances with its own intermediate-range missile force, deterring China through denial. Nonetheless, Tokyo is also considering both the deployment of longer-range strike missiles that could hit enemy territory, and development of its own hypersonic gliding vehicles. In fact, China's development of its hypersonic weapons questioned Japan's missile defense system's capacity to predict the course of incoming gliding missiles, a task that the US-developed Aegis Ashore system, designed to intercept and destroy incoming missiles, was unable to perform. Because of this reason, the system eventually needed to be scrapped. As a consequence, Japan's best defensive course was building up its offensive capabilities, on the premise that “tactically, having the option to go on the offensive will complicate the opponent's calculations”, as authoritatively pointed out by the Hudson Institute's Japan Chair Fellow, Masashi Murano, in a policy report.
Summing up, Japan has been, slowly but steadily, acquiring offensive capabilities in close coordination with the United States. As a result, Japanese defense policy is venturing into a new era. It however remains to be seen whether Japan can elaborate an appropriate retaliatory military doctrine and create a credible offensive counterforce – especially with only conventional weapons and warheads.
