
In December 2018, Japan will release its new National Defense Program Guidelines (NDPG), a defense policy document which also outlines the procurement plan entitled the Mid-Term Defense Program (MTDP) for the next five years. The current 2014 NDPG states that the Self-Defense Forces (SDF) should become able to fulfill their roles effectively in the following two new fields of warfare: outer space and cyberspace.

According to a recent media report, the upcoming NDPG will expand and build up the roles of SDF into the field of “electronic warfare.” What does it mean for Japanese security policy and the U.S. strategy toward the Indo-Pacific? Japan’s “going electromagnetic” will enhance the Japanese role in its own defense and also expand the bilateral defense cooperation in the context of the U.S. strategy toward the Indo-Pacific.

What Is Electronic Warfare?

In modern daily life, we are living in an electromagnetic (EM) spectrum environment. Remote TV controls, keyless car lock/unlock devices, and smartphones — these devices use a number of electronic sensors and EM transmissions. Today’s modern armed forces are also using the same technologies and coordinating operations effectively.

The U.S. Department of Defense defines electronic warfare (EW) as “military action involving the use of electromagnetic and directed energy to control the electromagnetic spectrum or to attack the enemy.” EW consists of three subcategories: (1) Electronic Attack (EA), which involves the use of EM energy, directed energy, or anti-radiation weapons to attack enemy forces and facilities; (2) Electronic Protection (EP), which involves the protection of friendly forces from any effects of friendly or enemy use of the EM spectrum; and (3) Electronic Warfare Support (ES) which refers to intelligence, surveillance and reconnaissance (ISR) at the operational level.

Enjoying this article? Click here to subscribe for full access. Just $5 a month.

The concept of EW is not new. The military’s use of the EM spectrum actually goes back farther in history than outer space and cyberspace. For example, during the Vietnam War the American EW capability succeeded in disrupting enemy radar sites and radar-guided surface-to-air missiles (SAM), then went on to destroy enemy targets while minimizing or preventing friendly damages.

After the September 11 attacks, however, the United States began shifting its focus from state actors to nontraditional actors such as terrorists and insurgents who have little EW capability (except for items such as an improvised explosive device (IED)). The United States could still dominate the EM environment against enemy-integrated air defense systems (IADS) in Iraq and Libya, but further investment in EW capability has remained a lower priority for more than a decade.

Why Is EW Now Becoming Critical in the Indo-Pacific?


The Chinese military strategy of anti-access/area denial (A2/AD) is a layered defense system of long-range missiles, aircraft, ships, and submarines, and it is designed to keep U.S. forces from intervening in a given area in the Indo-Pacific. Most importantly, in order to find targets and coordinate their attacks, all Chinese A2/AD systems depend on sensors and communications which operate in the EM spectrum. China is developing EW aircraft such as J-10D, and in June 2018, China tested their EW assets in the South China Sea.

In response, the U.S. military is currently discussing the concept of Multi-Domain Battle (or sometimes called Cross-Domain), which envisions all military assets working together to disrupt and destroy the enemy from all domains: land, sea, air, space, cyberspace, and the electromagnetic spectrum. This U.S. Army-led concept has not officially been shared yet by all four branches, but they seem to be moving in a similar direction. The U.S. Army plans to revise the concept this October, and the concept may become a joint concept in 2019.

Whatever the concept may be, it is impossible to succeed in conducting operations under the A2/AD environment without a reliable EM network. That is why it is critical now to build an EW capability to protect friendly EM networks as well as to disrupt (and destroy if necessary) the enemy EM networks in the Indo-Pacific. In June 2017, the Pentagon’s Deputy Director for EW William Conley clearly made this point by stating, “A2/AD is basically a fight in the electromagnetic spectrum.”

To meet growing EW challenges, the U.S. created a high-level Electronic Warfare Executive Committee in the Pentagon in 2015, made a first ever (classified) electronic warfare strategy in 2017, and included over $5 billion for EW in the 2017 defense budget.

Diplomat Brief Weekly Newsletter N Get first-read access to major articles yet to be released, as well as links to thought-provoking commentaries and in-depth articles from our Asia-Pacific correspondents. Subscribe Newsletter

What is the Current Japanese EW Capability?

The current Japanese EW capability focuses only on intelligence and training. The Maritime SDF (MSDF) has been operating five EP-3s (electronic data acquisition aircraft), five OP-3Cs (image data acquisition aircraft), one UP-3C (equipment testing aircraft), and three UP-3Ds (electronic warfare training support aircraft), while two YS-11EAs (electronic warfare training support aircraft) and four YS-11EBs (electronic data acquisition aircraft) have been operated by the Air SDF (ASDF). The obsolete YS-11EB (four or five decades old) will be replaced by four RC-2s (electronic data acquisition aircraft), the first of which just took a test flight in February.

The ASDF deployed the first F-35A stealth jet, which is equipped with the most advanced EW system, to Misawa Air Base in January 2018, and Japan plans to procure 42 F-35As. However, Russia delivered the first S-400 Triumf/SA-21 Growler SAM defense systems to China in March or April. The S-400 will become a challenging neighbor to the F-35. The S-400 can engage 36 targets at the same time, and every unit comes with eight launchers, each one of which is equipped with 32 missiles. China plans to acquire four to six S-400 systems. This 400-kilometer-range system enables China to strike aerial targets in Taiwan, New Delhi, Hanoi, Seoul, and China’s air defense identification zone (ADIZ) in the East China Sea.

Enjoying this article? Click here to subscribe for full access. Just $5 a month.

The overall Japanese EW capability is too limited to protect friendly forces from the effects of the enemy’s EW operations and to effectively attack enemy forces and facilities by using the EM spectrum. In order to catch up with its neighbors’ investment in EW capabilities, Japan is currently considering various options that aim to acquire an advanced capability of electronic attack (EA) and electronic protection (EP).

What EW Capability Is Japan Considering?

Japan has approximately 200 F-15 fighter jets but they have no stealth ability, so Japan plans to modify these F-15s in the next 2019 fiscal year to make them less reflective of radar signals and enable them to jam radar as well as defend against electronic attacks. Japan also aims to facilitate electronic information sharing and analysis within the SDF regarding other countries’ EW measures. This intelligence will be collected and reserved on the Japan Aerospace Defense Ground Environment (JADGE) network, an automated warning and air defense control system, to help SDF units respond against enemy EW attacks more effectively.


In addition, Japan is examining the possible procurement of advanced electronic attack aircraft that can disrupt and destroy enemy air defense and command systems within the range of several hundred kilometers. Options include the acquisition of Boeing EA-18G Growler, which emits large radio pulses to jam radar and communication systems, and also carries anti-radiation missiles (ARMs) to destroy radar facilities. The modification of ASDF’s C-2 transport aircraft or private jumbo jet into an electronic attack aircraft is also an option that Japan is considering.

The advanced EW capability will enhance the Japanese version of A2/AD capability, which aims to keep Chinese naval and air forces from intervening in Japan’s surroundings. Most importantly, the enhanced EW capability complicates the cost-benefit calculations of adversaries, which helps discourage the first aggressive acts of adversaries and strengthen effects of deterrence by denial.

Implications of an Enhanced EW Capability on Japanese Security Policy

The upcoming EW capability debate will certainly reinvigorate the public’s question of whether the enhanced EW capability goes beyond the exclusively defense-oriented policy (“Senshuboei” in Japanese) which Japan has maintained since the end of World War II. This declaratory policy means that defensive force is to be used only in the event of an attack, that the extent in the use of defensive force is kept to a minimum necessary for self-defense, and that the defense capabilities possessed and maintained by Japan are limited to the minimum necessary for self-defense.

Based on this policy, Japan has interpreted the constitutionality of attacking enemy bases narrowly. In 1956, the government released its legal position that it is possible to attack enemy installations under certain limits to forestall a deadly attack if there is a clear and present danger that Japan would face such an attack and when there is no means to protect the country from the danger. However, if Japan acquires electronic attack aircraft, Japan will become able to deploy these assets over international air space off the coast of adversaries to neutralize radar sites before the event of an attack against Japan happens.

Furthermore, the exclusively defense-oriented policy has been a logical foundation when the government explains the division of roles between the United States and Japan in the alliance. In this logic, Japan plays a defensive role (the “Tate” or shield in Japanese) in securing the Japanese homeland while the U.S. plays an offensive role (the “Hoko,” sword in Japanese) in striking enemy bases. Speaking technologically, the acquisition of EA aircraft alone will not complete the building of capabilities in attacking enemy bases. Japan will also have to acquire other assets such as a Joint Surveillance Target Attack Radar System (JSTARS) and increase its related capabilities, including manpower both in quantity and quality. But the enhanced EW capability will surely lead to domestic debates regarding the division of roles in the U.S.-Japan alliance.

Prime Minister Shinzo Abe confirmed the maintenance of Japan’s exclusively defense-oriented policy in April 2018, so the upcoming strengthening of EW capability will need further explanation in the context of this long-standing policy. For example, the enhanced EW capability would be used after Japan was kinetically attacked, in order to prevent subsequent attacks by enemy forces as a means of self-defense.

Implications of the Japanese EW Capability on the U.S. Strategy Toward the Indo-Pacific

In 2015, the United States and Japan revised the 1997 defense cooperation guidelines. The 2015 guidelines are described as a historic step for Japan to project its power globally or even become able to defend the United States for the first time. But we often fail to notice that the 2015 guidelines actually paved the route toward a greater Japanese role in its own defense. The 1997 guidelines used the phrase U.S. “strike power (Dagekiryoku)” three times and the Japanese “primary responsibility (Shutaiteki)” to defend the country six times, while the 2015 guidelines mention the U.S. “strike power” just once and the Japanese “primary responsibility” 12 times. The increase of Japanese EW capability is certainly on the right track within the 2015 bilateral defense cooperation guidelines.

More broadly, an enhanced Japanese EW capability may be able to become an important asset in the U.S. strategy toward the Indo-Pacific. It is not yet clear which joint concept will be shared by all four branches of the U.S. military in the end, but if the United States and its allies in the Indo-Pacific can operate a more advanced EW capability both in quantity and quality and deploy these capabilities in a distributed manner, it will make adversaries’ efforts to find targets and coordinate their attacks more complex. In the end, the dispersed sensors and lethal weapon networks in the region will enhance deterrence by influencing adversaries psychologically.

We do not know at this moment what EW capability Japan will decide to acquire and which joint concept the U.S. will create in order to cope with the A2/AD environment. But the U.S. military has its own mismatch problem between manpower and growing operational demands, as multiple accidents have recently occurred in the Indo-Pacific. How would the United States respond to possible consequences if Japan fails to increase its own “primary responsibility” to defend its own country? The new NDPG will be published in December, and it is certain that U.S. policymakers will be paying close attention.

Dr. Aki Nakai is an adjunct faculty in the Pardee School of Global Studies at Boston University and the Political Science Program at Lesley University