Politics, Energy, and Nationalism: Thailand and Cambodia’s Overlapping Maritime Claims

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Politics, Energy, and Nationalism: Thailand and Cambodia’s Overlapping Maritime Claims

The two countries have agreed to resolve their outstanding claims in the Gulf of Thailand, but will be forced to negotiate their way around a host of nationalist tripwires.

Politics, Energy, and Nationalism: Thailand and Cambodia’s Overlapping Maritime Claims

A sailboat sails in the Gulf of Thailand close to the port of Sihanoukville, Cambodia.

Credit: Depositphotos

The recent diplomatic activity between the Thai and Cambodian governments has reopened stalled talks on the overlapping sea claims of the two Southeast Asian nations.

The overlapping claims in the Gulf of Thailand date back to the early 1970s, when Cambodia claimed a maritime territory of 200 nautical miles of the continental shelf in line with the Convention on the Continental Shelf of 1958. This provoked the Thai government to respond with a similar claim in 1973. The area in dispute between Cambodia and Thailand covers roughly 27,000 square kilometers and holds an estimated 11 trillion cubic feet of natural gas. A similar overlapping claim between Malaysia and Thailand was resolved in 1979.

The overlapping claims area, or OCA, in the Gulf of Thailand is one of several border disputes between Thailand and its eastern neighbor that date back to the colonial period. Despite these issues, Thailand and Cambodia have had mutually beneficial and cordial relations in recent decades, especially when a government led by or aligned with Thaksin Shinawatra has been in power.

The warm interpersonal relations between Thaksin and long-time former Cambodian Prime Minister Hun Sen were seen last month when Hun Sen paid a personal visit to Thaksin three days after his parole and release from hospitalized confinement. It was notable that Hun Sen didn’t even bother to pay a courtesy call to Thai Prime Minister Srettha Thavisin.

With Thaksin’s Pheu Thai Party back in power, and Hun Sen’s son Hun Manet now in power in Cambodia, a path has opened to the resolution of the OCA issue. The subject was discussed during last month’s meeting between Srettha and Hun Sen’s son Prime Minister Hun Manet, who took over from his father in August. The two leaders also signed agreements covering scientific cooperation, joint EXIM bank cooperation, chambers of commerce, and customs clearance and indicated that they were ready to elevate Thai-Cambodia relations to a “strategic partnership.”

However, any attempt to resolve the bilateral disputes may reawaken nationalist sentiments that have periodically complicated relations between Cambodia and Thailand. While bilateral relations have generally been cordial, they have sporadically turned violent. The most notable recent incident was in 2003, when a Thai actress made uninformed claims that Angkor Wat was in fact a Thai heritage site. This prompted riots, reportedly encouraged by the Cambodian government, that resulted in attacks on Thai-owned businesses and the torching of the Thai Embassy in Phnom Penh.

Tensions once again arose in 2008, after UNESCO listed the disputed Preah Vihear temple, an eleventh-century Angkorian ruin, as a World Heritage Site. This angered “yellow shirt” Thai nationalists who had helped Prime Minister Abhisit Vejjajiva come to power, with the help of the Thai army, earlier in the year. This culminated in a series of contained but intense border clashes between the two militaries in the vicinity of Preah Vihear, followed by further minor clashes in 2010 and 2011.

Outstanding Maritime Disputes

Bilateral negotiations over the OCA are governed by a Memorandum of Understanding signed between Thailand and Cambodia in 2001. The MoU has at its core a few important principles. First, the overlapping claims north and south of 11 degrees latitude are conjoined and must be negotiated in parallel. The 11-degree line divides disputed territorial seas, which extend 12 nautical miles off the coast, from the broader area delimited for natural resource exploitation.

Second, given that there is no termination clause, if any party wishes to terminate the MOU, this must be agreed to by both parties jointly. Last, the conclusion of negotiations must be inclusive of areas north and south of the 11th latitude – i.e., the entirety of the OCA.

Of late there have been exploratory talks on exploiting national gas reserves which are believed to exist to the far south of the disputed maritime territory, reminiscent of the Thailand-Malaysia OCA agreement signed in 1979. The problem with this approach is that the contested Cambodian claims intersect with Thailand’s Koh Kood island. This has reignited Thai nationalist sentiment, with critics claiming recently that the Thai government is willing to give up Koh Kood in exchange for natural gas. This, of course, is not true, but is putting Srettha and his Pheu Thai government in a difficult position of its own making.

Credible rumors have it that Thai and Cambodian officials have at the highest level agreed to the above and that this will be sealed when Thaksin’s daughter Paetongtarn Shinawatra visits Cambodia later this month.

How this might be managed poses a political challenge for the Thai government. Its current approach is to agree to joint natural resource exploitation in the southern OCA and continue negotiating the northern claims separately. The problem, however, is that this would violate the 2001 MoU. To get around this, the Ministry of Energy and the prime minister have allegedly been pushing for the termination of the 2001 MOU or at least a legal workaround to settle the claims separately.

This has pitted Thai ministers against the Thai bureaucracy, whose members do not want to be blamed or take legal risks by agreeing and signing off on the Thai government plan for fear of facing charges of dereliction or wrongful exercise of duty under Article 157 of the 2017 Constitution. If found guilty bureaucrats who sign off on politicians’ agenda could face up to a decade in prison.


Even if it can manage this, there is the possibility of running into nationalist tripwires. If the current Thai government moves forward with its plans jointly to exploit natural gas in the southern OCA without settling contested claims to Koh Kood and the northern area it risks reigniting nationalist sentiment on both sides of the border.

The Thai government risks blowback from Thai nationalists for “giving up” or putting into question Thai claims to Koh Kood in the northern OCA. This is of course a red herring but current discourse in Thailand is rigid on the question of Thai sovereignty over Koh Kood. The Cambodian government also risks inflaming nationalist sentiment if it is seen to be giving up its own claims to the island. If the plans move forward, moreover, Thailand will lose all leverage over future negotiations, as Cambodia will have achieved its goal of energy exploitation whilst leaving its claims in the north for a later day.

If the Srettha government is seen to surrender Thai sovereignty, it could reawaken old sentiment regarding Thaksin from his previous opposition and spark a nationalist fervor. The recent past shows that conflict between the two countries is possible and given Thaksin’s proximity to the issue following his return to Thailand last year, there is a small but significant possibility of a new border conflict between the two neighbors.

Given Thailand’s dwindling natural gas reserves and attendant increases in expensive LNG imports and Cambodia’s failed energy revolution, the time is right for a deal. Thaksin still has enormous political capital and his relationship with Hun Sen is still as strong as ever. The time is ripe to bring closure to this long-standing dispute – if nationalists on both sides can be held in check.