China has nine maritime neighbors (including Taiwan) but no settled maritime boundaries, due in part to Beijing’s unwillingness to specify its maritime claims. Only one partial exception to this imprecision exists: a boundary agreement with Vietnam to delimit the northern part of the Gulf of Tonkin and a fishery agreement establishing a joint fishing regime in that area, both reached in 2000.

The agreements offer both positive and negative lessons. At a minimum, they provide important precedents that should be more widely appreciated – foremost among them that it is possible for China to come to the bargaining table on maritime disputes. Meanwhile specific lessons can be applied to China’s bilateral maritime disputes with Japan, Vietnam, and the Koreas. Unfortunately the Tonkin agreements support only modest expectations for resolution of the complex, multilateral Spratly Islands disputes.

First, the good news:

1. The Tonkin agreements might have enabled future deals:

Leaders in both China and Vietnam authorized their diplomats to negotiate formal boundaries governing about 36,000 square nautical miles of productive fisheries and potentially lucrative hydrocarbons. The deal emerged from three separate rounds of negotiation (1974, 1978-1979, and 1992-2000), with the last being a whole-of-government effort featuring input from senior party leaders, provincial governments, various stakeholder agencies, and technical and scientific experts. Importantly, growing familiarity between negotiators did not breed contempt – rather, it helped establish organizational and individual connections that were indispensable to the final settlement. Wang Yi, the current PRC foreign minister, was China’s lead negotiator and presumably knows what is required, politically and organizationally, to achieve future settlements. Comparable, substantial investment of official time and political energy is possible and necessary for future deals.

2. China made significant compromises:

The 21 geographic points constituting the Sino-Vietnamese boundary in the Gulf of Tonkin divide it into two unequal parts, with 53.23 percent of the water lying on the Vietnamese side of the line. This compromise by China reflects the relative length of the Vietnamese coastline and the position of Bach Long Vi Island. That island was once the subject of a Sino-Vietnamese sovereignty dispute put to rest in 1957 when Mao Zedong and Zhou Enlai dropped the Chinese claim. That strong Chinese leaders were once willing to make a deal over sovereignty that later facilitated a boundary resolution is a valuable precedent.

3. UNCLOS provided guidelines, but was not determinative:

The conclusive round of Sino-Vietnamese negotiations (1992-2000) was facilitated by the parties’ informal agreement in 1993 that the United Nations Convention on the Law of the Sea (UNCLOS) would furnish the basic principles to be applied to resolving maritime boundary disputes. They also agreed that international practice, equity, and relevant circumstances would be given appropriate weight in negotiations. The parties did not use their respective interpretations of the law of the sea as take-it-or-leave-it demands for comprehensive settlement. Rather, international law furnished several focal points for the two parties (who had not yet even ratified UNCLOS) to cooperate and delimit their respective territorial seas, exclusive economic zones (EEZs), and continental shelves. This nuanced approach to legal norms allowed them to reach agreement even while “shelving” pesky problems such as rights over non-living resources like oil and gas.

4. The agreement gave partial effect to islands and reduced maritime entitlements:

The states’ overlapping EEZs in the area were given less than the maximum 200 nautical miles prescribed in UNCLOS. Further, Vietnam’s Bach Long Vi and Con Co Islands were given 25 percent and 50 percent effect, respectively, in drawing the demarcation line for those EEZs. This compromise established an immensely valuable precedent for future negotiations over Chinese maritime boundaries in the East and South China Seas. Partial effects would be especially valuable in the bilateral dispute with Japan over the Senkaku (Diaoyu) Islands, which lie at the very southern end of a long potential maritime boundary and could be effectively ignored in delimitation. This move might prove even more useful in the bilateral dispute with Vietnam over the Paracel Islands, where mutual agreement to reduce (or ignore) entitlements for the Paracels would allow extension of the Tonkin demarcation line through that disputed area without addressing the question of sovereignty over the islands.

5. Domestic objections did not scuttle the deal:

Nationalist sentiments ran high in both China and Vietnam after the deal was announced. The four-year lag between the parties’ signing the agreements (2000) and putting them into effect (2004) is partly attributable to public protests, media criticism, and bureaucratic resistance to the compromises on both sides. Leaders in both countries mustered the political will to conclude the deal in spite of strong domestic objections, and could do so again if they truly wanted to.

Now for the bad news.

1. The boundary agreement covers only a small area:

Though better than envisioned in the original talks, which covered about one third of the maritime space eventually delimited, the roughly 300-mile line eventually established bisects only a small fraction of the disputed area. No official talks about extending the line have been reported, and subsequent practice south of the delimited area has not been cooperative.

2. The agreement did not involve disputed features:  

Notwithstanding the 1957 Chinese concession on Bach Long Vi, China and Vietnam established their maritime boundary in the Tonkin Gulf by neglecting (both geographically and diplomatically) complex issues arising from sovereignty disputes. Although the “partial effects” precedent can mitigate that complexity and narrow the scope of disputed zones, the fact remains that China would need to muster significantly greater political courage to even begin talks that might touch upon its “indisputable” sovereignty claims over features in the South and East China Seas.

3. Implementation of the fishery agreement is iffy:

The Tonkin boundary agreement is permanent and requires no implementation, but the fisheries agreement has a 12-year lifespan (and a 3-year automatic extension), and must be constantly upheld in practice if it is to be meaningful. Based on limited reporting, implementation has not been an overwhelming success. The effectiveness of an international maritime boundary depends largely on the activities of vessels, especially private fishing vessels, from both sides. Judging from collapsing fish stocks in the South China Sea, rampant illegal fishing, and frequent conflicts between law enforcement and private fishermen from China and Vietnam, the agreement’s terms are still mostly aspirational. The only permanent organ established by China and Vietnam to manage implementation is a Joint Fishery Committee tasked with managing a Common Fisheries Zone. It meets once or twice per year to consult on conservation and utilization of fishery resources, but has had little verifiable success in making fisheries and law enforcement cooperation the norm in the delimited area.

4. The agreed boundary relied on a historical treaty not a generic principle:

The delimitation line in the Tonkin agreement does not strictly apply any standard that can be replicated for other disputed boundaries. The agreed boundary does not appear to be based on an equidistant line between the two coasts, but rather on an 1887 Sino-French treaty that provided a mutually agreeable starting point for delimitation. Unfortunately, given the ambiguity of the post–World War II disposition of islands in the East China Sea and the existence of multiple, contradictory historical bases for claims in the South China Sea, the “historical treaty” precedent is inapplicable to outstanding disputes.

5. Sino-Vietnamese diplomatic relations are more robust than others:

In spite of deep historical distrust between China and Vietnam, the long-standing relationship between their respective Communist parties greatly aided the negotiation process. By contrast, China’s diplomacy with Japan is badly under-institutionalized and frequently interrupted by nationalism and other domestic pathologies. The intensive, institutionalized negotiations required for successful boundary agreements would pose a special problem in that deeply fraught bilateral relationship. So too with the Philippines, toward which China is particularly negative after Manila launched arbitration proceedings that Beijing considers illegitimate. Negotiations with Brunei, Indonesia, and Malaysia would present less severe diplomatic obstacles, but any settlement with them would require negotiations with other, less amenable parties to be practically meaningful.

6. China was in a more compromising mood in the 1990s:

Between 1991 and 1999, China signed 11 boundary agreements that fully or partially settled seven disputes along its land borders. One of those was the Chinese land boundary with Vietnam, with which the maritime boundary agreement was associated. Unfortunately for China’s neighbors, that compromising mood is only a fond memory. Today China appears less vulnerable and more confrontational than in the wake of the 1991 collapse of the Soviet Union and the diplomatic isolation that followed the 1989 Tiananmen Square protests. Nationalism concerning the East and South China Sea disputes is not new, nor is it necessarily more virulent or uncompromising, but China’s position has hardened and its capacity to enforce its claims and dictate terms of future settlements has increased.

On balance, the Sino-Vietnamese boundary and fishery agreements are a promising sign that China is capable of substantial compromise in maritime disputes. The agreements established several precedents that ought to be remembered and publicized. Modesty about the agreements’ wider applicability is also necessary. Still, Chinese leaders and experts, in particular, should be encouraged to review the diligent process and salutary outcome of that earlier era of diplomatic compromise as they set out to stabilize China’s troubled maritime frontier and secure a peaceful rise.