Why the U.S. is Not Invoking International Law to Oppose China’s ADIZ

China’s East China Sea Air Defense Identification Zone (ADIZ) has spawned tons of media commentary, so much so that I have had little to add and can barely keep up with all the coverage. Still, there is one small legal point that bears some further discussion.  While I think the U.S. is correct as a matter of policy to push back against China’s ADIZ, the legal framework underlying the U.S. position is awkward and borderline incoherent.  In fact, the confusing U.S. legal position may explain why the U.S. is not sympatico with Japan on China’s ADIZ.  Let me explain.

It is worth noting that U.S. has not condemned China’s ADIZ as a violation of international law. Instead, the U.S. has called it “unacceptable” and a change in the “status quo”.  Meanwhile, the Chinese have wielded international law as a rhetorical weapon on their side, by citing the U.N. Charter from the outset.  This may seem odd, but in fact, the Chinese are sort of right about this.

As Peter Dutton notes in his AJIL article, establishing an ADIZ is not in itself a violation of international law,  Indeed, it is usually justified by a need to create an early warning system to protect national airspace.  China’s ADIZ seems pretty large (map can be found here), and the U.S has rightly complained that aircraft just transiting the ADIZ should not be subject to China’s requirements if those airlines are not planning to enter (or even come near to) Chinese national airspace.

But China’s ADIZ is carefully drawn to include two sets of islands/rocks that it claims as sovereign territory: the Senkakus/Diaoyu (also claimed by Japan) and the Ieodo/Suyan Rock (also claimed by South Korea).  To the extent those territories are “national airspace”, China can argue that it should be allowed to draw an ADIZ around them to ensure any airplanes coming near them will not enter that airspace, etc.  As Zachary Keck suggests, China is using the ADIZ to subtly build its legal claim to sovereignty over the Senkakus/Diaoyu Islands. Hence, China is probably invoking the UN Charter’s self-defense provision to justify its ADIZ and its need for all foreign aircraft to report flight info/etc. when entering the ADIZ.  (Some commenters to my first post have suggested China can’t invoke self-defense over a disputed territory, or uninhabited islands that don’t otherwise threaten its national airspace.  I am not sure the customary practice is clear on this, since Japan’s ADIZ, which also covers the Senkakus/Diaoyu, couldn’t be justified either under this view. Also, for the purposes of this post, I am assuming China has a plausible claim to the islands).

Seen from this perspective (at least vis-a-vis the U.S.), China’s ADIZ is not inconsistent with any existing international agreement or customary legal rule.  This is largely because of the strange and confusing U.S. position on the sovereignty over the Senkakus/Diaoyu Islands.  The U.S. does not take any official position on which country (China, Taiwan, or Japan) has sovereignty over these islands.  But it recognizes that Japan has administration over them (indeed, it was the U.S. that turned them over to Japan back in 1972) and the U.S. has repeatedly declared that such islands fall within the scope of the U.S.-Japan Defense Treaty.But since the U.S. does not recognize Japanese sovereignty over the Senkaku/Diaoyu Islands, why should it complain when China draws an ADIZ intended to protect airspace over those islands?

This wrinkle in the U.S. position also explains Japan’s harsher reaction to the Chinese ADIZ. To Japan, China is literally demanding Japanese airlines report to its military before crossing airspace into or near Japan’s own national airspace.  It would be like China demanding information from US airlines flying between San Francisco and Hawaii (Congress would explode with indignation).  But from the U.S. perspective, China is just demanding information about airlines flying near disputed airspace that may or may not be part of China anyway.  This is a threat to freedom of international air navigation, but it is not anything like the same kind of affront to sovereignty that it is to the Japanese.

The U.S. position would be more legally coherent if it would simply recognize Japan’s sovereignty over the Senkakus/Diaoyu.  After all, if the U.S. Navy is willing to fight and die for these islands, the U.S. should at least decide whose owns these islands. (If China creates an ADIZ in the South China Sea, the U.S. will also have the same dilemma. See Michael Kelly’s recent essay on the strategic implications of such an ADIZ).  China is subtly probing the U.S. position here, and it has opened up a slight wedge between the U.S. and Japan.  But this wedge is a result of contradictions in the U.S. legal position, not China’s clever diplomacy.