As the Thai-Cambodian Joint Boundary Commission (JBC) convenes in Phnom Penh on Saturday amid rising tensions, Prasart Prasasvinitchai, leader of the Thai delegation, faces a defining moment after his appointment was welcomed by those who view him as a seasoned negotiator, but drew caution from others who see him as too divisive a figure to calm such a sensitive diplomatic issue.
A long-serving official at the Ministry of Foreign Affairs, Mr Prasart has made a career out of interpreting international law and advising in boundary negotiations. Trained in law, he is known for his precision and deep institutional knowledge, having risen through the Department of Treaties and Legal Affairs, where he once headed the boundary division before serving as director-general. His background has made him a go-to figure in many of Thailand's most delicate border talks.
He has held ambassadorial roles in Phnom Penh, Manila, Kuwait, and Yangon. Yet it is his time in Cambodia that continues to define his reputation.
In 2009, under the Abhisit Vejjajiva administration, tensions escalated after Cambodia appointed former prime minister Thaksin Shinawatra, who went into self-imposed exile in 2008, as an adviser to then-Cambodian prime minister Hun Sen. The Thai government saw it as interference and recalled Mr Prasart, then ambassador to Phnom Penh, in protest. He resumed his post in August 2010.
Mr Prasart has also faced criticism from nationalist groups and civic networks who viewed him as being too conciliatory towards Cambodia. Critics such as former People's Alliance for Democracy (PAD) leader Sondhi Limthongkul and Veera Somkwamkid strongly opposed his appointment.
Their objections stem largely from the Dec 29, 2010 incident when Veera and six other Thai nationals were arrested by Cambodian troops while inspecting disputed border areas near Preah Vihear Temple and Ban Nong Jan near Sa Kaeo province. Charged with illegal entry, trespassing and espionage, Veera served three years in a Cambodian prison. He later alleged that then-ambassador Prasart pressured him to recognise Cambodian sovereignty. Veera also accused him of harassment and warned that Mr Prasart's leadership would undermine Thailand's national interests.
Sondhi also accused Mr Prasart of siding with Cambodia in 2010, claiming he urged detainees to accept Cambodian claims. "We cannot trust someone like this to defend Thai sovereignty," he said.
At a Foreign Ministry briefing on Thursday, spokesperson Nikorndej Balankura defended Mr Prasart: "He is technically proficient, well respected and fully aware of both the historical and legal complexities".
Mr Nikorndej also stressed that the Thai delegation comprises senior representatives from the military, National Security Council, Royal Thai Survey Department, Hydrographic Department of the Navy, and Foreign and Interior ministries.
On Monday, General Songwit Noonpakdee, Chief of Defence Forces, was appointed as an adviser, underscoring the strategic importance of the talks, in which Mr Prasart must again walk a tightrope between diplomacy and distrust.