The Pentagon invoked a U.S. defense treaty with Japan and warned China on Saturday that its declaration of an air defense zone over the East China Sea is increasing the danger of military conflict.
Both Secretary of State John Kerry and Defense Secretary Chuck Hagel issued statements late Saturday expressing "deep concern" over China’s creation of the air defense identification zone, or ADIZ, that extends over Japan’s Senkaku Islands, which China claims as its territory.
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"We view this development as a destabilizing attempt to alter the status quo in the region," Hagel said. "This unilateral action increases the risk of misunderstanding and miscalculations."
Hagel then reaffirmed the U.S. military commitment to the 1952 U.S.-Japan Mutual Defense Treaty.
"The United States reaffirms its longstanding policy that Article V of the U.S. Japan Mutual Defense Treaty applies to the Senkaku Islands," Hagel said.
A reference to the defense treaty is the clearest sign that the Pentagon fears China will use the creation of a new air defense zone to block U.S. and Japanese aircraft or ships from passing through the zone that includes large areas of international waters.
Such actions could set off the use of force and a military confrontation.
A Chinese map of the new defense zone shows that it overlaps Japan’s defense zone over the Senkakus.
China’s defense ministry warned in a statement Saturday that all aircraft that fail to comply with new Chinese rules for transit through the zone could be shot down.
"China's armed forces will adopt defensive emergency measures to respond to aircraft that do not cooperate in the identification or refuse to follow the instructions," the ministry said in a statement.
In Tokyo, the government called China’s action "very dangerous" and said it would not accept territorial encroachment over the Senkakus.
Junichi Ihara, chief of the Foreign Ministry’s Asian and Oceania Affairs Bureau, protested the action to an official at the Chinese Embassy in Tokyo, according to a ministry statement. Ihara told the Chinese that Japan would "never accept the zone set up by China" because it covers the Senkakus. Creation of the defense zone also will "escalate" tense relations and he said the move was "very dangerous," Agence France Presse reported from Tokyo.
The U.S.-Japan defense treaty obligates U.S. military forces to act against any attack against Japan or the United States within Japanese territorial administration, waters that include the Senkakus, a group of uninhabited islands located south of Okinawa and north of Taiwan.
Until the announcement of the defense zone, the Obama administration had sent mixed signals to China regarding its maritime encroachment. It initially said it remained neutral in the dispute and belatedly said the Senkakus are covered by the U.S.-Japan defense accord.
A defense official said China has steadily stepped up tensions with Japan over the past year and that has increased the risk China will use its growing and increasingly technically advanced military forces to take action against Japan.
The United States was not notified in advance by China of the new zone, a defense official said. The lack of notification highlights the failure of both the diplomatic and military engagement policies toward China by the Obama administration.
Observers note that the unilateral action of setting up the defense zone also contradicts Chinese President Xi Jinping’s recent call for creating a new type of major power relationship with the United States.
Kerry, fresh from concluding a nuclear deal with Iran in Geneva that will permit Tehran to continue enrichment of uranium, also said the United States is "deeply concerned" by China’s air defense zone over East China Sea.
"This unilateral action constitutes an attempt to change the status quo in the East China Sea," Kerry said in a statement. "Escalatory action will only increase tensions in the region and create risks of an incident."
Kerry said free overflight and sea transit are essential for the stability and security of the Pacific.
"We don't support efforts by any state to apply its ADIZ [air defense identification zone] procedures to foreign aircraft not intending to enter its national airspace," he said.
"We urge China not to implement its threat to take action against aircraft that do not identify themselves or obey orders from Beijing."
Kerry said the United States has urged China to "exercise caution and restraint" and added that consultations are underway with Japan and other states.
Hagel said the declaration of the ADIZ by China "will not in any way change how the United States conducts military operations in the region."
The U.S. position is being conveyed to China through military channels, he said.
Former State Department China specialist John Tkacik said he was concerned by Kerry’s mild rebuke of the Chinese in saying that the United States did not support China’s action.
"The phrase ‘we don't support’ in diplomatese means something quite different from the phrase ‘we oppose,’" Tkacik said. "They convey a disagreement in principle, but lack of commitment to do anything about it."
Tkacik noted that during the George W. Bush administration when Taiwan sought to alter the status quo, the U.S. government clearly stated it is opposed to any change in the status quo.
The Chinese will read the response as weakness, he said.
"I'm afraid this soon will force Washington's hand. The ADIZ covering the Senkakus has been under Japanese or U.S. administration for 70 years; and the Senkakus have been Japanese-U.S. administered for 120 years," Tkacik said. "If Washington decides that the U.S. does not have a dog in this fight, even though the U.S. Air Force invented the existing ADIZ's in the 1950s, it's curtains for the U.S.-Japan alliance."
China for the past several months has been encroaching on waters near the Senkakus by sending maritime surveillance vessels and more recently naval warships, warplanes, and unmanned aircraft through the region.
The defense zone was announced on Saturday by the Chinese Defense Ministry. The ministry said in a statement that the zone included new rules for aircraft flying in the region.
The rules require aircraft to provide flight planning data for flights through the zone, and aircraft must maintain radio contact with Chinese air controllers.
All aircraft must use transponders that will allow the Chinese to track the flights through the zone, and must be properly marked.
Chinese interceptor aircraft conducted the first flights into the zone after it went into force at 10:00 am local time on Saturday, according to news reports from the region.
Chinese Defense Ministry spokesman Yang Yujun said through state-run media that the ADIZ was created to "identify, monitor, control and react to aircraft entering this zone with potential air threats."
"The Chinese government sets up the East China Sea Air Defense Identification Zone with the aim of safeguarding state sovereignty, territorial land and air security, and maintaining flight order," he said. "This is a necessary measure taken by China in exercising its self-defense right. It is not directed against any specific country or target. It does not affect the freedom of over-flight in the related airspace."
Yang said other air defense zones are being considered. The zone applies only to military aircraft and commercial aviation will not be affected, he said.
In the South China Sea, China has triggered maritime disputes with Vietnam, Philippines and several other states by declaring that 90 percent of the sea is Chinese territory. An air defense zone over the South China Sea could be a next step.
In addition to a potential conflict with Japan over its air and sea patrols over the Senkakus, the new zone will limit U.S. intelligence-gathering flights.
In 2001, a Chinese interceptor jet collided with a U.S. EP-3 surveillance flight near the same region, setting off a crisis.
The Chinese pilot was killed when his aircraft crashed in the East China Sea. The U.S. crew made an emergency landing and was held captive by the Chinese until being released later.