Has China begun the construction of its fourth “Great Wall,” in the sky over the East China Sea? The famed “Great Wall,” constructed from roughly 220 B.C. up to the Ming dynasty in the 16th century, is a World Heritage site. Mao Zedong ordered the establishment of a “Great Wall at Sea” in the 1950s, and the “Great Firewall” has become well-known in the in cyber world over the past decade.
The idea of a Great Wall in the Sky goes back to at least 2009. On the 60th anniversary of the People’s Liberation Army Air Force (PLAAF) on November 1, 2009, the People’s Daily published an article titled “Building a Great Wall in the Blue Sky,” and the Xinhua News Agency ran an interview with the commander of the PLAAF, Xu Qiliang, titled “Building a Great Iron Wall in the Blue Sky.” Until the last decade, the idea of a Great Wall at sea or in the sky was pure fantasy, or a mere slogan at best. Even now, after Beijing’s sudden declaration of its “Air Defense Identification Zone (ADIZ)” in the East China Sea on November 23, the PLAAF lacks the capability to cover all of the ADIZ declared, specifically lacking sufficient capabilities in 1) land based radar coverage; 2) aerial refueling; and 3) air early warning and control.
Nevertheless, in its November 23 proclamation, China’s Ministry of National Defense declared that it would begin enforcing its rules in its ADIZ at 10:00 a.m. that same day. The rules demand that any aircraft flying in the ADIZ must: report a flight plan to the Chinese government, maintain radio communication and respond to identification inquiries from the Chinese government, maintain radar transponder function, and exhibit clear nationality and logo markings. And the announcement warned that “China’s armed forces will adopt defensive emergency measures to respond to aircraft that do not cooperate in the identification.”
Defense ministry spokesman Col. Yang Yujun said in a press briefing that “this is a necessary measure taken by China in exercising its self-defense right” and “it is not directed against any specific country or target.”  Part of Col. Yang’s answer to the question “Why is the boundary of the Zone only 130 km away from some country’ [sic] territory?” was, “some country established Air Defense Identification Zone as early as in 1969. The shortest distance from their zone to the Chinese mainland is also 130km.” That provided suggestive evidence that the zone is directed against specific countries―such as Japan, which established its ADIZ in 1969.
Prior to that, the lines of existing ADIZs in the region were drawn by the U.S. military after World War II and during the Korean War, acknowledging different countries’ de facto valid control over their territories. These lines were taken over by South Korea, Japan, and Taiwan with the intention of avoiding an accidental clash. Therefore, there is very little overlap between existing ADIZs in Northeast Asia. To name a few examples, the Japanese ADIZ does not include Dokdo/Takeshima island, disputed with South Korea, or the Kuril Islands which are disputed with Russia.
China unilaterally established its ADIZ over two-thirds of the East China Sea without any consultation these neighbors. Consequently, there is now a huge amount of overlap with other’s ADIZs. At the same time, the Chinese ADIZ includes not only the Senkaku/Diaoyu Islands but also some joint training airspaces of the U.S. Air Force and the Japan Air Self-Defense Force, as well as U.S. military firing and bombing ranges in the East China Sea. In addition to the lack of consultation, China did not provide any “get acquainted” period; as noted above, the rules took effect the morning of the announcement.
The unilateral nature of this measure led to serious objections from China’s neighbors, including the United States. South Korea’s foreign ministry expressed formal regrets over China’s new ADIZ on November 24. Japan also asserted serious concern about the establishment of the Zone and its rules “which are profoundly dangerous acts that unilaterally change the status quo in the East China Sea, escalating the situation, and that may cause unintended consequences.” Secretaries John Kerry and Chuck Hagel conveyed their concerns about the Zone in statements on November 23. Kerry said that “this unilateral action constitutes an attempt to change the status quo in the East China Sea” and Hagel claimed that “this announcement by the People’s Republic of China will not in any way change how the United States conducts military operations in the region.”
Now that China has declared the ADIZ and asserted its right to enforce it in certain ways, the critical question going forward is how exactly it will exercise its self-proclaimed rights. On November 30, PLAAF spokesperson Shen Jinke said at a press briefing that the PLAAF scrambled jet fighters and verified two military reconnaissance aircraft from the United States and identified 10 Japanese jet fighters in the new Chinese ADIZ. Soon after this, However, Japan’s defense minister said he didn’t acknowledge the Chinese scramble against Japanese jet fighters.
If China’s pursuit of its “counter-intervention operation” strategy, widely known among western experts as “anti-access/area denial” strategy (A2/AD), is any guide, China’s enforcement of the ADIZ in the future will likely increase military activities by a number of regional powers, and thereby raise tensions and possibilities for an accident.
China has implemented the A2/AD strategy, vis-à-vis America’s “freedom of navigation” or “freedom of the sky,” to protect the South China Sea, Taiwan, and the East China Sea from incursion by the U.S. military in times of emergency, and has accelerated its military modernization in line with this strategy. For successful A2/AD, the People’s Liberation Army Navy (PLAN) will have to advance beyond the first island chain (including, loosely, Borneo, the Philippines, Taiwan, the Ryukyu Islands, and mainland Japan) and out into the Pacific Ocean. The frequency of PLAN fleets passing through the first island chain into the Western Pacific has been increasing: from two times each in 2008 and 2009, four times in 2010, five times in 2011, 11 times in 2012, to 10 times in the first eight months in 2013.
The tension between militaries in the East China Sea and Western Pacific has increased as China has expanded its operations. On September 8, 2013, two Chinese H-6 strategic bombers flew over the Miyako Strait, which Japan designates an international strait and air space between the main island of Okinawa and Miyako islands and is a gateway to the Western Pacific Ocean. It is the first time on record that Chinese strategic bombers have flown across the first island chain and into to Western Pacific. The following day, the JSDF observed an unidentified unmanned aerial vehicle (UAV) flying over the East China Sea near the Senkaku/Diaoyu Islands.  The JSDF assessed that the UAV came from mainland China and was Chinese military equipment, which was subsequently admitted by the Chinese Ministry of National Defense.  Even though these strategic bombers flying without support of fighters remain quite vulnerable to U.S. and Japanese anti-aircraft capabilities, the series of Chinese attempts to burst through the islands chain leaves the United States and Japan with lingering suspicions about China’s intentions.
In late October 2013, Chinese naval fleets conducted a “groundbreaking” joint military drill named the “Maneuver 5” in the Western Pacific. Ten naval ships from the Northern, Eastern, and Southern Fleets crossed the first island chain and gathered in the sea area between the first and the second island chain of small archipelagos in the Western Pacific with the support of two H-6 strategic bombers and two Y-8 airborne early warning and control planes. A senior military researcher in the PLA Academy of Military Science said that “the so-called first island chain has been dismembered by the three major fleets of the PLAN”; the report added that the “blockade” no longer exists. Considering the PLAN’s lack of fleet area air-defense capability, Chinese military officials exaggerate the accomplishment of running through the first islands chain.
In pursuing its A2/AD strategy, China will have to sail through the waters surrounding the Senkaku/Diaoyu Islands and pass the Sakishima Islands. In fact, during the past three years, the Chinese navy has repeatedly sailed through the Miyako Strait to conduct exercises in the western Pacific Ocean. As the gateway to the Miyako Strait, the Senkaku Islands are emerging as a key strategic point that could play a decisive role in the A2/AD strategy.
In part for this reason, in the past few years a cycle of hostile action and reaction over the Senkaku/Diaoyu Islands has heated up between Japan and China. In response to these military excises, Tokyo has increased reconnaissance visits to PLAN’s activities and conducts counter measure military drills around Japan’s southern islands. Soon after the PLAN’s drills in the Western Pacific in October, Japan conducted an 18-day military exercise in November. The joint land, sea, and air exercise included 34,000 soldiers, six naval vessels, and 340 aircraft and was the largest military drill in Japan’s history after WWII. It was the first time for Self Defense Force of Japan to position its Type-88 surface-to-ship missiles close to the Miyako Strait―the PLAN’s gateway to the Western Pacific. PRC defense ministry spokesman Yang Yujun accused that Japanese ships and aircrafts interfered in China’s normal training activities and warned that “China reserves the right to take further measures.”
China has begun to expand its periphery outward in the ocean with the emerging “core interests” strategy or “maritime power strategy,” both of which intend purely to ensure its national security by the way of setting up buffer zones on its coastlines. The ADIZ can be seen is another effort at creating a buffer zone. But both the fact creating these buffer zones, the opaque and sometimes confrontational methods by which China is creating them, and the resulting increased tempo of military activities by a number of countries will likely cause trouble and incidents over coastal and littoral areas with its neighbor countries.
During this process, even small incidents at sea or in the air between China and its neighbors cause negative assessments about the intentions of the other side. This leads to misperceptions of the actions and intentions of the other side and finally results in a negative spiral of action, reaction, and rising tension. In this context, China’s efforts to construct the new “Great Wall in the Sky” over the East China Sea will be mistakenly considered as that of a rising dragon seeking to evict the eagle from its nest; this will cause serious damage to regional security and stability.
 Bernard D. Cole, The Great Wall at Sea: China’s Navy Enters the 21st Century, US Naval Institute Press, 2001.
 Also referred to as the “Golden Shield Project,” initiated in 1998 and in operation since 2003.
 People’s Daily, “蓝天筑长城 (Building a Great Wall in the Blue Sky),” November 1, 2009.
 Xinhua News Agency, “筑蓝天钢铁长城 (Building Great Iron Wall in the Blue Sky),” November 1, 2009.
 “Statement by the Government of the People’s Republic of China on Establishing the East China Sea Air Defense Identification Zone,” Ministry of National Defense of the PRC, http://eng.mod.gov.cn/Press/2013-11/23/content_4476180.htm.
 “Announcement of the Aircraft Identification Rules for the East China Sea Air Defense Identification Zone of the P.R.C.,” Ministry of National Defense of the PRC, http://eng.mod.gov.cn/Press/2013-11/23/content_4476143.htm.
 “Defense Spokesman Yang Yujun’s Response to Questions on the Establishment of The East China Sea Air Defense Identification Zone,” Ministry of National Defense of the PRC, http://eng.mod.gov.cn/Press/2013-11/23/content_4476151.htm.
 Yonhap News, “S. Korea expresses regrets over China’s ADIZ,” November 25, 2013. http://english.yonhapnews.co.kr/national/2013/11/25/46/0301000000AEN20131125004252315F.html.
 “Statement by the Minister for Foreign Affairs (of Japan) on the announcement on the ‘East China Sea Air Defense Identification Zone’ by the Ministry of National Defense of the People’s Republic of China,” Ministry of Foreign Affairs of Japan, http://www.mofa.go.jp/press/release/press4e_000098.html.
 “Statement on the East China Sea Air Defense Identification Zone,” U.S. Department of State, http://www.state.gov/secretary/remarks/2013/11/218013.htm.
 “Statement by Secretary of Defense Chuck Hagel on the East China Sea Air Defense Identification Zone,” U.S. Department of Defense, http://www.defense.gov/releases/release.aspx?releaseid=16392.
 See Andrew Krepinevich, Barry Watts and Robert Work, “Meeting the Anti-Access and Area-Denial Challenge,” Center for Strategic and Budgetary Assessments, 2003.
 Ministry of Defense of Japan, “The security environment around Japan,” p. 8.
 Press release on September 9, 2013, Joint Staff of Japan Self Defense Force (JSDF).
 Press release on September 9, 2013, Joint Staff of JSDF.
 Jiji Press, September 10, 2013.
 Xinhua News Agency, November 2, 2013.
 “Chinese navy breaks through island chains blockade,” Ministry of National Defense of the PRC, October 23, 2013. http://eng.mod.gov.cn/Opinion/2013-10/23/content_4472067.htm.
 “China accuses Japan of interfering in naval drills” Associated Press, October 31, 2013. http://bigstory.ap.org/article/china-accuses-japan-interfering-naval-drills.