Recently, international observers have been puzzled to see Malaysia undertaking oil and gas operations in the overlapping extended continental shelf area defined by its 2009 joint submission with Vietnam to the Commission on the Limits of the Continental Shelf (CLCS). As reported by AMTI, the West Capella, a drillship contracted by Malaysian national oil and gas company Petronas, entered and began operations within the “Joint Defined Area” on December 21, 2019. This move has provoked a three-way standoff between Malaysia, China, and Vietnam involving warships, coastguard, militia, and civilian vessels. Why would Malaysia choose to ignore its 2009 joint submission with Vietnam and undermine ASEAN solidarity?

Whatever its motivations, Malaysia should err on the side of caution. Instead of venturing into undertakings in the Joint Defined Area which may not be lawful, Malaysia should consider doing what is certain to be consistent with international law.

Unilateral Exploration May Be Unlawful

Under the United Nations Convention on the Law of the Sea (UNCLOS), the Joint Defined Area between Malaysia and Vietnam should be considered as having “pending status” on two fronts. First, it is a continental shelf pending delimitation between states with opposite or adjacent coasts. And second, it is an extended continental shelf claim beyond 200 nautical miles which is still awaiting recommendations from the CLCS.

Concerning the first category, UNCLOS requires relevant states not to jeopardize or hamper the reaching of a final agreement on delimitation. International tribunals have recognized this as an obligation to avoid unilateral invasive activities in undelimited areas. In the Guyana/Suriname case in 2007, the arbitral tribunal stated that unilateral exploratory drilling in an undelimited or disputed area which causes physical change to the marine environment may jeopardize or hamper the reaching of a final agreement on delimitation. The arbitral tribunal found that less invasive exploratory activity in a disputed area, such as seismic surveying, could be permissible.

In the more recent Ghana/Côte d’Ivoire case, the International Tribunal for the Law of the Sea (ITLOS) allowed preexisting unilateral operations to continue in disputed areas pending the judgement of the tribunal, but prohibited new drilling. The tribunal found in its 2017 judgement that drilling undertaken by Ghana had not prejudiced Côte d’Ivoire’s sovereign rights, but only because the area in question was ultimately attributed to Ghana, which had acted in good faith on that assumption. If the tribunal had delimited the maritime boundary in favor of Côte d’Ivoire, then Ghana’s unilateral operations would have indeed prejudiced Côte d’Ivoire’s sovereign rights.

Given that the West Capella is a drillship, it can be assumed that Malaysia is engaged in unilateral drilling, not just less invasive surveys. Malaysia might be assuming in good faith that the part of the Joint Defined Area in question would be awarded to it in any eventual delimitation. But it also recognized that the area is disputed when it made the joint submission to the CLCS in 2009, so undertaking new drilling in the area now falls short of the precedent set by Ghana/Côte d’Ivoire.

Regarding extended continental shelf areas beyond 200 nautical miles, UNCLOS remains silent on what rights and obligations coastal states have while their claims are still pending recommendations from the CLCS. International tribunals have so far only provided very general guidance on that subject, finding that activities should not prejudice the rights of third parties or the international community. Given that the Joint Defined Area lies in disputed waters and has not received a recommendation from the CLCS, would unilateral exploration be considered an activity that prejudices those rights? The answer may again depend on whether the operation causes physical change to the marine environment. In the case of drilling, the answer would certainly be yes.

Delimitation: The Safer Course

A closer look at judgments and awards from international tribunals relating to extended continental shelf claims that are awaiting recommendations from the CLCS shows that one activity that is surely consistent with international law is the delimitation of this area between the states involved. Various tribunals have stated that delimitation does not prejudice the rights and interests of third-party states or the international community. Nor can it be seen as encroaching on the function of the CLCS because the commission’s role in delineating the outer limits of the continental shelf is distinct from delimiting its lateral limits between two states. ITLOS was clear on the matter in its judgement in Bangladesh/Myanmar: “There is nothing in the Convention [i.e. UNCLOS] or in the Rules of Procedure of the Commission [i.e. CLCS] or in its practice to indicate that delimitation of the continental shelf constitutes an impediment to the performance by the Commission of its functions.”

From this perspective, Malaysia could begin discussions with Vietnam about delimiting the Joint Defined Area. The two countries could choose to do it by way of negotiations or adjudication. While the greater degree of control over the process offered by negotiation seems to make it the preferred practice for maritime delimitation for South China Sea states, adjudication has some important advantages for Malaysia in this case. First, it could be faster. Boundary negotiations can last for decades without agreement whereas ITLOS or an ad hoc arbitral tribunal would take about three years to reach a decision. Second, Malaysia has significant experience in settling maritime disputes using third party mechanisms, having initiated four different proceedings, one of which involved both ITLOS and arbitration under Annex VII of UNCLOS (i.e. the case concerning Land Reclamation in and around the Straits of Johor). Last but not least, a decision from an international tribunal could help reinforce the validity of the joint submission made by Malaysia and Vietnam. In cases such as Bangladesh/Myanmar and Ghana/Côte d’Ivoire, ITLOS went so far as to examine relevant parties’ submissions to the CLCS itself to conclude that they had entitlements to an extended continental shelf beyond 200 nautical miles even when the CLCS had not yet issued a recommendation.

Delimitation may be a slower and less eye-catching way for Malaysia to affirm its sovereign rights and jurisdiction in the Joint Defined Area than simply undertaking unilateral drilling. But it is the only way forward that is guaranteed to be lawful. Even more importantly, it can help avoid confrontations like the current three-way standoff, which carries a risk of instigating a larger conflict and undermines ASEAN unity.


The author would like to thank Ms. Pham Ngoc Minh Trang and Mr. Duong Danh Huy for their help in the completion of this commentary.

About Vu Hai Dang

Vu Hai Dang is a Senior Research Fellow at the Centre for International Law, National University of Singapore.