
In an ordinary week, an agreement about the Diaoyu / Senkaku Islands, a disputed area that has triggered a series of standoffs between China and Japan in recent years, would have been big news.

Such an agreement was signed this week, albeit not between China and Japan –rather Japan and Taiwan, which also claims the islands as part of its territory, have reached a deal that will allow Taiwanese fisherman to use the majority of the Japanese-controlled zone around the islands.

Although the deal is framed as an interim agreement, delaying resolution of claims of ownership, it promises to change the dynamics of the East China Sea. It removes the main source of friction between Taiwan and Japan but creates a variety of problems for the Chinese government, which fears both diplomatic isolation on territorial issues and a revival of Taiwan's diplomatic status. It could also signal an important strategic shift as China's eastern neighbors borrow an approach from the Philippines and Vietnam.

The deal has significant advantages for both Taiwan and Japan: it significantly expands the reach of Taiwan's fishermen, which is a boon for the island's economy, and starts the area on a road toward a sharing agreement such as those proposed by President Ma Ying-Jeou and former Vice President Annette Lu. Japan will no longer have to deal with protests from Taiwanese fishermen, who have been a frequent cause of tension, and will pull Taiwan toward its side of the issue.

Immediate reaction from Beijing has focused on the issue of Taiwan's status. Comments from the foreign ministry reminded Japan of a commitment to respect the "One China" policy, while the Global Times criticized Taiwan for ingratitude: "Although there has been no open cooperation between the mainland and Taiwan on the Diaoyu Islands issue, tacit understandings do exist. The strong stance from the mainland side in safeguarding the sovereignty of the islands has undoubtedly strengthened Taiwan's status in its negotiations with Japan."

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For mainland observers, this was the second time in as many months Japan has acted to undermine its policy towards Taiwan – the last being a commemoration of the second anniversary of the Fukushima disaster during which Taiwan's representative was treated as an ambassador.

The agreement also deprives the mainland of a rare issue on which it can position itself as a defender of Taiwan's rights – until now, the mainland navy has gleefully stressed its willingness to protect Taiwanese fisherman from the Japanese Coast Guard, and Beijing has proposed the islands as an area for cooperation with Taiwan.

The islands no longer seem ripe for cooperation – in fact, the head of Taiwan's Coast Guard said on Wednesday that Taiwanese ships will help Japan to keep mainland trawlers out of the disputed area, raising the prospect of an embarrassing mainland China-Taiwan standoff.


But China also has reasons to worry about its own claim to the islands. If Japan and Taiwan can come to a compromise, they may be able to cast the mainland as the unreasonable party standing in the way of resolution, thus winning international support.

Taken together with the Philippines' bid for international arbitration in the South China Sea, this agreement risks making China a territorial pariah. Jerome Cohen, a distinguished expert on Chinese law, argued at a recent event that the two cases suggest a trend toward using international law as a "defensive weapon" by East Asian countries concerned about being overwhelmed by China.

Cohen said that Japanese officials have floated the idea of taking the case to the International Court of Justice in recent months – a move which seems pretty farfetched, as it would first require Japan to recognize that there is a dispute. But, Cohen said, the threat of using international law may constrain China, which frequently cites its respect for bodies like the ICJ and UNCLOS in efforts to build its soft power – often contrasting its role in UN peacekeeping missions with the U.S.' willingness to fight wars without Security Council clearance. However, appealing to international law would risk Japan's losing some or all of its claimed territory. But this week's agreement suggests that such a calculus may appeal to Japan's current leaders. It may be that they care more about keeping China from getting the islands than keeping them for Japan.