Desmond Ball and Richard Tanter
August 6, 2015
NAPSNet Special Report
I. Introduction
This is a study of Japan’s ground-based signals intelligence (SIGINT) stations, the 17 (soon to be 19) major facilities that intercept, monitor, collect, process and analyse foreign electronic signals. Official statements convey nothing of the scale or detail of the Japanese SIGINT effort, which is probably the third or fourth largest SIGINT establishment in the world. These Japanese ground signals interception and location facilities are integrated with its air and missile defence radar facilities. Together with Japan’s own long-range underwater surveillance systems, and combined with the Japan-based US parallel air, ground and underwater surveillance systems, they take Japan a very long way towards its stated aim to ensure information supremacy in the region. As potentially lucrative targets in the event of war, destruction of these important but vulnerable facilities could alter escalation dynamics in such a way that the widespread assumption that a Japan-China armed conflict could be controlled before substantial escalation may not hold true.
This report is a visual guide, hopefully making it easier for those who come after us to identify what they are seeing. Similar and comparable systems are critical to the strategic planning of all countries with substantial military capacities – or ambitions. Accordingly an understanding of the Japanese ground stations, their physical characteristics, and the logic of their deployment may be of use in understanding non-Japanese systems.
Authors
Desmond Ball is Emeritus Professor at the Australian National University (ANU). He was a Special Professor at the ANU’s Strategic and Defence Studies Centre from 1987 to 2013, and he served as Head of the Centre from 1984 to 1991.
Richard Tanter is Senior Research Associate at the Nautilus Institute and Honorary Professor in the School of Political and Social Sciences at the University of Melbourne.
Chapter 1
Japan’s postwar signals intelligence (SIGINT) facilities were maintained from 1958 to 1997 by a small unit of the Japan Ground Self Defence Force (JGSDF) known as the Chobetsu or Chosa Besshitsu. More formally the Annex Chamber, Second Section, Second Investigation Division of the JGSDF, the Chobetsu reported directly to the Cabinet Research Office, later named the Cabinet Intelligence and Research Office. Today Japan’s extensive signals intelligence (SIGINT) network of facilities are managed by the Defense Intelligence Headquarters, a special (or ‘attached’) organization within the Ministry of Defense, headed by an SDF lieutenant-general.
In 1978, the Asahi newspaper published a detailed account of Japan’s SIGINT establishment, based on an interview with a senior officer of the Japan Defence Agency (JDA), which described the organisation of the Chobetsu and the location of its intercept stations, and gave some examples of their activities. The Chobetsu then managed and operated nine SIGINT stations. These were located at Wakkanai, at the northwestern point of Hokkaido; Nemuro and Higashi Nemuro, at the northeastern point of Hokkaido; Higashi Chitose in the southwestern part of Hokkaido; Kobunato and Miho on the western side of Honshu, facing the Sea of Japan; Ooi, near Tokyo; Tachiarai in northern Kyushu; and Kikai-jima in the northern part of the Ryukyu island chain, about half-way between Kyushu and Okinawa.[x] Another station was constructed on Okushiri Island off the southwest coast of Hokkaido in the 1980s. In 1991-93 there was ‘a rapid expansion of Japan’s ELINT/SIGINT gathering capabilities’ at the main stations in Hokkaido – Chitose, Wakkanai, Nemuro, and the ‘recently-established’ station at Okushiri.[xi]By this time, smaller stations had also been established at Rebun Island, Maruyama, Shibetsu, and Rausu in northern Hokkaido.[xii] A new large JASDF SIGINT station was built at Seburi-yama in northwestern Kyushu in 2004-06, another was completed at Miyako-jima in 2009-10, and another at Fukue-jima was scheduled for completion in 2014.[xiii]
There are now 17 SIGINT stations of one sort or another maintained by the DIH, JGSDF or JASDF, with an eighteenth under construction at Yonaguni, Japan’s southwestern-most island, and a nineteenth at Iwoto (Iwo Jima), Japan’s southeastern-most island. (See Map 1 and Table 1) Some of these are sub-stations of larger stations, but located in different areas better situated for specific monitoring functions. For example, the JGSDF’s No. 301 Coastal Surveillance Unit based at Wakkanai maintains a substantial station at Maruyama, near Cape Soya, just northeast of Wakkanai, as well as on Rebun Island, in the northeast part of the Sea of Japan, west of Wakkanai. The JGSDF unit at Shibetsu, No. 302 Coastal Surveillance Unit, has facilities at Rausu, on the Shimokita Peninsula northwest of Shibetsu and slightly closer to the Russian-occupied island of Kunashiri, and at Nemuro, which is better placed for high frequency direction finding (HF DF) and some electronic intelligence (ELINT) functions. (Map 2)
The management arrangements are sometimes quite complex, involving several agencies and a variety of host-tenant relationships. In addition to the Radio-wave [or SIGINT] Department of the Defense Intelligence Headquarters (DIH) at Ichigaya, the JGSDF and the other Services also have important operational and administrative roles. The JGSDF’s 2nd Defence Intelligence Division Detachment has primary responsibility for operation of the eight major SIGINT stations at Wakkanai, Nemuro, Chitose, Kobunato, Ooi, Miho, Tachiarai and Kikai-jima. The JGSDF’s No. 301 Coastal Surveillance Unit is a tenant unit at the large Wakkanai station, but is the primary organisation at Maruyama and Rebun Island; No. 302 has its own station near Shibetsu (Kawakita), but is a tenant at the JASDF’s SIGINT station at Nemuro. Other JGSDF Coastal Surveillance Units maintain SIGINT facilities on Tsushima Island, while a new unit was set up at Izumo in Shimane Prefecture in March 2008, facing the southwestern part of the Sea of Japan. In addition to maintaining a network of about 15 ELINT stations concerned with ocean surveillance, the JMSDF has units at most of the large DIH/JGSDF stations.[xiv] At Wakkanai, for example, the JMSDF unit is simply called ‘JMSDF Wakkanai Base Detachment Unit’. The JASDF’s Air Intelligence Collection Unit No. 1 is a tenant unit at Wakkanai; Unit No. 2 has its own facility on the northeast side of Nemuro township; and No. 3 is the primary unit at the Okushiri station. JASDF Air Intelligence Collection Units maintain the new SIGINT stations at Seburi-yama, Fukue-jima and Miyako-jima.
Some of the stations are very large, involving Circularly-disposed Antenna Arrays (CDAAs) known as ‘elephant cages’, and maintained by more than a hundred personnel, such as those at Chitose, Miho and Kikai-jima. The JASDF’s new J/FLR-4 and J/FLR-4A stations at Seburi-yama, Fukue-jima and Miyako-jima are also quite large, involving a huge operations building and two large towers holding extensive antenna suites. The JASDF’s Air Intelligence Collection Units are typically comprised of about 80-100 personnel.
The JASDF’s J/FLR-2, J/FLR-3, J/FLR-4 and J/FLR-4A systems comprise a suite of antenna elements for intercepting VHF, UHF and SHF signals. These systems have been built by Toshiba since the late 1980s, beginning with the J/FLR-2 at Nemuro, and are technically and operationally direct descendants of the US AN/FLR-12 system at Wakkanai, bequeathed to Japan in 1972.
On the other hand, several stations are small and physically unimpressive, such as the No. 302 Coastal Surveillance Unit’s facility at Rausu. Numerous different types of antenna systems are employed at the various stations. In addition to the large elephant-cage CDAAs, there are many smaller CDAAs, various sorts of Adcock direction-finding (DF) arrays, rhombic arrays, log-periodic antennas, satellite communications antennas, and assorted VHF, UHF and SHF systems for ELINT collection.
Seven of the major DIH/JGSDF stations have HF DF systems. The huge ‘elephant cages’ at Miho, Chitose and Kikai-jima are the most sensitive. They can intercept HF signals out to a range of about 5,000 km or more, with a bearing accuracy of about one-half of a degree. A new 7-element system was installed at Wakkanai, Nemuro, Kobunato and Tachiarai in 2008-10. It consists of seven masts, about 13 metres high, deployed in a circle with a radius of 40 metres, a circumference of about 351.33 metres and a distance between each mast of about 36 metres (Plate 1). At Wakkanai, Nemuro and Kobunato, these replaced 36-element CDAAs, with two concentric circular arrays of 18 masts covering the lower and higher parts of the HF band, which had been built in 1988, 1991-92 and 1988 respectively (Plates 2a, b, and c). At Tachiarai, the new 7-element system replaced an old 8-element HF DF array. Similar systems had previously been at Miho, Kobunato and Kikai-jima, but were dismantled when their larger CDAAs became operational. Another 8-element HF DF array was at Ooi.[xv] (Plate 3)
Many stations also have VHF and UHF DF systems for determining the location of line-of-sight VHF and UHF emitters. In northern Hokkaido, for example, there are VHF and UHF DF systems at the JGSDF SIGINT stations at Wakkanai, Rebun Island, Maruyama, Rausu, Nemuro (2) and Higashi Nemuro (Plate 4).
In addition to monitoring line-of-sight VHF communications, Japan is favourably placed for interception of VHF signals from thousands of kilometers away to the southwest due to an anomalously high electron density in the Sporadic E layer (Es) of the ionosphere over the East China Sea. It has been shown, for example, that VHF broadcast transmissions from China in the 39.75 to 72.25 MHz range are clearly receivable in Japan using both Yagi and log-periodic dipole arrays.[xvi] Indeed, VHF signals transmitted in Southeast Asia, including from Malaysia and the Philippines, can also propagate to Japan via the Es layer.[xvii]
Many of the stations are located at sites used for SIGINT operations before or during the Second World War, and which had been proven to be especially lucrative. For example, the sites at Wakkanai/Noshyappu (野寒布岬)[xviii] and Nemuro were in December 1944 two of the Japanese Navy’s largest SIGINT stations, with the former covering the area around the northern part of the Sea of Japan and the southern part of the Sea of Okhotsk, and the Nemuro station covering a broad swath of the northern Pacific Ocean.[xix] The Imperial Navy also maintained a large SIGINT station for intercepting Soviet communications at Shibata, not far from the present station at Kobunato.[xx] Other sites were selected by the US in the 1950s and 1960s for intercepting signals in the Soviet Union, such as at Chitose, where the US station was transferred to Japan in 1971.
There have been few major changes at any of the stations targeted on Russia since the early 1990s. On the other hand, the capabilities of those stations primarily engaged in intercepting North Korean and Chinese signals have been substantially enhanced since the late 1990s, and especially since the early 2000s. The Miho station had reportedly established an ancillary COMINT facility at nearby Takao-yama by 1998, giving it better access to North Korean VHF signals. Ten radomes with satellite communications antennas have been installed at Tachiarai since 2002, and the new CDAA was opened at Kikai-jima in 2006. The three new JASDF J/FLR-4 and J/FLR-4A stations are directed primarily against Chinese signals. The two latest stations, currently under construction at Yonaguni and Iwoto, will both also be concerned primarily with Chinese signals.
To read the full 238-page report, including dozens of greats photographs, maps and charts, click here,
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