CRS Report for Congress
Prepared for Members and Committees of Congress
Senkaku (Diaoyu/Diaoyutai) Islands Dispute:
U.S. Treaty ObligationsMark E. Manyin
Specialist in Asian Affairs
September 25, 2012
Congressional Research Service
7-5700
www.crs.gov
R42761Summary
Since the mid-1990s, tensions have spiked periodically among Japan, China, and Taiwan over the
disputed Senkaku Islands in the East China Sea. These flare-ups run the risk,
which most observers regard as remote, of involving the United States in an armed conflict in the
region. Japan administers the eight small, uninhabited islands, which some geologists believe sit
near significant oil and natural gas deposits. China and Taiwan both contest Japanese claims of
sovereignty over the islands.U.S. administrations going back at least to the Nixon Administration have stated that the United
States takes no position on the territorial disputes. However, it also has been U.S. policy since
1972 that the 1960 U.S.-Japan Security Treaty covers the islands, because Article 5 of the treaty
stipulates that the United States is bound to protect “the territories under the Administration of
Japan” and Japan administers the Senkakus. Under the treaty, the United States
guarantees Japan’s security in return for the right to station U.S. troops—which currently number
around 50,000—in dozens of bases throughout the Japanese archipelago. Although it is
commonly understood that Japan will assume the primary responsibility for the defense of the
treaty area, in the event of a significant armed conflict with either China or Taiwan, most
Japanese would likely expect that the U.S. would honor its treaty obligations.Each time tensions over the islands have flared, questions have arisen concerning the U.S. legal
relationship to the islands. This report will focus on that issue, which has four elements:
1. U.S. administration of the Senkakus (Diaoyu Islands) from 1953 to 1971;
2. the application to the Senkakus (Diaoyu Islands) of the 1971 “Treaty Between
Japan and the United States of America Concerning the Ryukyu Islands and the
Daito Islands”—commonly known as the Okinawa Reversion Treaty, approved
by the Senate in 1971 and entered into force the following year (the Daito Islands
lie to the east of Okinawa);
3. the U.S. view on the claims of the disputants; and
4. the relationship of the U.S.-Japan Security Treaty to the islands.
Members of Congress periodically have been involved or expressed interest in the Senkaku
dispute over the decades, most prominently when the issue of the U.S.-Japan Security
Treaty’s application arose during the Senate’s deliberations over the Okinawa Reversion Treaty.
More recently, Congressional committees have explored the topic in hearings about maritime
disputes in East Asia.Introduction
Periodically, tensions arise among Japan, China, and Taiwan over a small group of islands located about 120 miles northeast of Taipei, Taiwan. Japan, China (also known as the People’s Republic
of China, or PRC), and Taiwan (also known as the Republic of China, or ROC) all claim
sovereignty over the islands, known as the Senkakus in Japan, the Diaoyu in China, and the
Diaoyutai in Taiwan. China considers the islands to be part of Taiwan, over which it claims
sovereignty. The islands are eight in number, sometimes described as five islets and three rocks,
and are uninhabited. The largest is about two miles in length and less than one mile in width.
However, geologists believe that the waters surrounding them may be rich in oil and natural gas
deposits.The disputed claims are long standing. Most recently, tensions have flared in 2012 following
Tokyo governor Shintaro Ishihara’s April 2012 announcement in Washington, DC, that he
intended to lead a movement to purchase three of the eight islands from their private owner.
Ishihara, who is known for expressing nationalist Japanese views, called for demonstrating
Japan’s control over the islands by building installations such as a telecommunications base, a
port, and a meteorological station. He conducted an online campaign to support his efforts,
raising nearly $20 million in private donations for the purchase. In a move it said was designed
to prevent Ishihara or other nationalists from acquiring the islands, Japan’s central government on
September 12, 2012, purchased the three islands for ¥2.05 billion (about $16 million at an
exchange rate of ¥78:$1). China and Taiwan protested the move, and across China large-scale
anti-Japanese protests erupted, some of which resulted in violence. Since Ishihara’s April 2012
speech, the islands also have been the scene of increased activity—and sometimes direct
encounters—between activists, fishermen, and maritime vessels of all three governments. Many
observers worry that an accident could result in armed conflict between Japan and China.Each time tensions erupt over the islands, questions have arisen concerning the U.S. relationship
to the islands. This report will focus on that issue. It was originally written by Larry Niksch, who
retired from CRS in 2010. It has been updated and modified slightly from the original.The Competing Claims
The claims of China and Taiwan have a similar basis. China asserts that its Ming Dynasty (1368-1644) considered the islands part of its maritime territory and included them on maps and documents of areas covered by Ming Dynasty coastal defenses. China claims that the Qing
Dynasty (1644-1911) went further and placed the islands under the jurisdiction of Taiwan, which was a part of the Qing Dynasty.2 In 1893, the Dowager Empress of China, Cixi, made a grant of
the islands to Sheng Xuanhuai, head of the Imperial Household, who collected medical herbs on them.3 However, although there are claims that Chinese fishermen used the islands as places of
temporary shelter and repair, China never established a permanent settlement of civilians or military personnel on the islands, and apparently did not maintain permanent naval forces in
adjacent waters.
Japan, which argues that there is no territorial dispute, laid claim to the islands in January 1895, when the Japanese Emperor approved an Imperial Ordinance annexing them to Japan. Before
then, Japan argues, the islands were uninhabited and “showed no trace of having been under the control of China,” positions the Chinese and Taiwanese governments reject. In May 1895, Japan
and the Qing Dynasty government of China signed the Treaty of Shimonoseki ending the Sino-Japanese war that had begun the previous year. Under the Treaty, which China today considers one of a number of “unequal treaties” forced on it by foreign powers, China ceded Taiwan
(Formosa) to Japan “together with all the islands appertaining or belonging to the said island of Formosa.” The Treaty did not specifically mention the Senkakus and the islands were not discussed during the negotiating sessions. Japan has claimed from this that its incorporation of the Senkakus (Diaoyu/Diaoyutai) was an act apart from the Sino-Japanese War.
In contrast, China and Taiwan argue that Japan used its victory in the war to annex the islands. They also argue that the intent of the Allied declarations at Cairo and Potsdam during World War
II was to restore to China territories taken from it by Japan through military aggression. In October 1945, when Japan relinquished authority over Taiwan, it did not specifically mention the
disposition of the Senkakus .U.S. Administration of the Islands, 1953-1971
U.S. administration of the islands began in 1953 as a result of the 1951 Treaty of Peace with
Japan.9 The Treaty did not mention the Senkakus, but it referred to other
islands that had reverted to Chinese control or which China claimed. These included Taiwan, the
Pescadores (off the western coast of Taiwan), as well as the Spratlys and the Paracels (both in the
South China Sea). Article 3 gave the United States sole powers of administration of “Nansei
Shoto south of 29 north latitude (including the Ryukyu and the Daito Islands)....” In 1953, the
U.S. Civil Administration of the Ryukyus issued U.S. Civil Administration of the Ryukyus
Proclamation 27 (USCAR 27), which defined the boundaries of “Nansei Shoto [the southwestern
islands] south of 29 degrees north latitude” to include the Senkakus. At the time of the signing
of the Okinawa Reversion Treaty, several State Department officials asserted that following the
signing of the Japan Peace Treaty, “Nansei Shoto south of 29 degrees north latitude” was
“understood by the United States and Japan to include the Senkaku Islands.” Moreover, during
the period of U.S. administration, the U.S. Navy established firing ranges on the islands and paid
an annual rent of $11,000 to Jinji Koga, the son of the first Japanese settler of the islands. China
has described the U.S.-Japan understandings related to the islands as “backroom deals” that are
“illegal and invalid.”Inclusion of the Senkakus in the Okinawa Reversion Treaty
The Okinawa Reversion Treaty, which was signed on June 17, 1971, and entered into force on
May 15, 1972, provided for the return to Japan of “all and any powers of administration,
legislation and jurisdiction” over the Ryukyu and Daito islands, which the United States had held
under the Japan Peace Treaty. Article I of the Okinawa Reversion Treaty defines the term “the
Ryukyu Islands and the Daito Islands” as “all territories with their territorial waters with respect
to which the right to exercise all and any powers of administration, legislation and jurisdiction
was accorded to the United States of America under Article 3 of the Treaty of Peace with
Japan....” An Agreed Minute to the Okinawa Reversion Treaty defines the boundaries of the
Ryukyu Islands and the Daito islands “as designated under” USCAR 27. Moreover, the latitude
and longitude boundaries set forth in the Agreed Minute appear to include the Senkakus
(Diaoyu/Diaoyutai). A letter of October 20, 1971, by Robert Starr, Acting Assistant Legal Adviser
for East Asian and Pacific Affairs—acting on the instructions of Secretary of State William
Rogers—states that the Okinawa Reversion Treaty contained “the terms and conditions for the
reversion of the Ryukyu Islands, including the Senkakus.”U.S. Position on the Competing Claims
During Senate deliberations on whether to consent to the ratification of the Okinawa Reversion
Treaty, the State Department asserted that the United States took a neutral position with regard to
the competing claims of Japan, China, and Taiwan, despite the return of the islands to Japanese
administration. Department officials asserted that reversion of administrative rights to Japan did
not prejudice any claims to the islands. When asked by the Chairman of the Senate Foreign
Relations Committee how the Okinawa Reversion Treaty would affect the determination of
sovereignty over the Senkakus, Secretary of State William Rogers answered that
“this treaty does not affect the legal status of those islands at all.” In his letter of October
20, 1971, Acting Assistant Legal Adviser Robert Starr stated:The Governments of the Republic of China and Japan are in disagreement as to sovereignty
over the Senkaku Islands. You should know as well that the People’s Republic of China has
also claimed sovereignty over the islands. The United States believes that a return of
administrative rights over those islands to Japan, from which the rights were received, can in
no way prejudice any underlying claims. The United States cannot add to the legal rights
Japan possessed before it transferred administration of the islands to us, nor can the United
States, by giving back what it received, diminish the rights of other claimants. The United
States has made no claim to the Senkaku Islands and considers that any conflicting claims to
the islands are a matter for resolution by the parties concerned.Successive U.S. administrations have restated this position of neutrality regarding the claims,
particularly during periods when tensions over the islands have flared, as in 1996, 2010, and
2012.The U.S.-Japan Security Treaty and the Islands
The inclusion of the Senkakus in the Okinawa Reversion Treaty under the definition of “the
Ryukyu Islands and the Daito Islands” made Article II of the Treaty
applicable to the islands. Article II states that “treaties, conventions and other agreements concluded
between Japan and the United States of America, including, but without limitation to the Treaty of
Mutual Cooperation and Security between Japan and the United States of America ... become
applicable to the Ryukyu Islands and the Daito Islands as of the date of entry into force of this
Agreement.” Using “Okinawa” as shorthand for the territory covered by the Treaty, Secretary of
State Rogers stated in his testimony before the Senate Foreign Relations Committee that the
Security Treaty “becomes applicable to Okinawa” in the same way as it applied to the Japanese
home islands. Deputy Secretary of Defense David Packard, in his testimony, stressed that Japan
would assume the “primary responsibility” for the defense of the treaty area but that the Security
Treaty was applicable.In short, while maintaining neutrality on the competing claims, the United States agreed in the
Okinawa Reversion Treaty to apply the Security Treaty to the treaty area, including the Senkaku.
During a 2010 worsening of Japan-PRC relations over the islands, Secretary
of State Hillary Clinton summed up the U.S. stance by stating, “... with respect to the Senkaku
Islands, the United States has never taken a position on sovereignty, but we have made it very
clear that the islands are part of our mutual treaty obligations, and the obligation to defend
Japan.”It also should be noted that in providing its consent to U.S. ratification of the Treaty, the Senate
did not act on the advice of several committee witnesses that it include a reservation concerning
the Senkakus in the resolution of advice and consent to ratification.
Moreover, the Security Treaty itself declares in Article V that each party would act “in accordance
with its constitutional provisions and processes” in response to “an armed attack ... in the
territories under the administration of Japan.” “Administration” rather than “sovereignty” is the
key distinction that applies to the islands. Since 1971, the United States and Japan have not
altered the application of the Security Treaty to the islands.The Japan-China Dispute over Their Maritime Boundary
Japan and China are involved in another East China Sea disagreement over maritime boundary (as opposed to the
competing claims over the territorial sovereignty of the Senkaku. While China claims the whole
continental shelf to the Okinawa Trough, Japan claims the same shelf to a median line between its undisputed
territory and that of China. Since at least the 1970s, China has been exploring and building pipelines on and around its
side of the median line in the disputed waters, under which are oil and gas deposits. In the first decade of the 2000s,
Japan and China began to pursue a bilateral agreement over the exploitation of the undersea hydrocarbon resources.
In their negotiations, both Beijing and Tokyo sought to make a distinction between their territorial dispute over the
Senkakus and the rights to develop the undersea hydrocarbon fields.
In June 2008, the two sides announced an agreement on joint exploration for gas and oil in two of the fields close to
or straddling the “median line” that Japan claims is the rightful boundary between the two countries’ 200-mile
exclusive economic zones (EEZs). The United Nations Convention on the Law of the Sea (UNCLOS) defines an EEZ
as the area extending from a country’s coastline outwards up to 200 nautical miles from the edge of a country’s
territorial sea, which ends 12 miles from its coastline. The Japan-China joint development explicitly states that it does
not prejudice either side’s legal claims in the area. Under the agreement, the two countries reached an
“understanding” for cooperation in the Chunxiao gas and oil fields (called Shirakaba in Japanese), the southernmost of
the fields. To date, however, no progress has been made in implementing the agreement.
It is unclear to what extent and in which situations the U.S.-Japan Mutual Security treaty, which refers to an armed
attack on the territories of under the administration of Japan, would apply in the event of a Sino-Japanese military
conflict over the two countries’ maritime boundary dispute. Regardless of the treaty’s technicalities and its
interpretation, however, it is likely that Japanese policymakers and citizens would expect that the treaty would apply
to any Sino-Japanese military conflict, including those involving the competing maritime claims.Author Contact Information
Mark E. Manyin
Specialist in Asian Affairs
mmanyin@crs.loc.gov, 7-7653
まだ読み終わっていないけれど参考資料として。