Cambodia's decision to split with ASEAN over a maritime dispute in the South China Sea “put a spotlight on ASEAN and make[s] every move that Cambodia makes significant”, according to a high-ranking official at the US Center for Strategic and International Studies.

Michael J Green, a former assistant to president George W Bush on Asian security affairs, held a public lecture yesterday to discuss the future of US-China relations and their impact on Cambodia. The lecture was a joint effort between the US Embassy and the Cambodian Institute for Cooperation and Peace.

Earlier this month, Cambodia, Laos and Myanmar refused to issue a joint statement with ASEAN, claiming the issue was between China and the Philippines only. Cambodia also joined China in preemptively dismissing The Hague’s pro-Philippines verdict.

Green said Cambodia’s decision not to stand with ASEAN would undermine the regional organisation. “ASEAN is not dead or finished,” Green said, “but just how much can we expect from them?” Green also expressed concern that if ASEAN is perceived as ineffective, the US would revert back to focusing only on “bilateral relations with the major players”.

Green expressed fears officials at home would be unimpressed with Cambodia’s loyalty to China and may want to focus resources on a more pliable ally.

However, he vowed to vouch for Cambodia back in the US.

“I’m going to make the argument that the US should expand cooperation with Cambodia,” he said.

A strong Cambodia was an independent Cambodia, he said. “The more resilient Cambodia becomes, the better they can resist the influence of more powerful countries.”

Phoak Kung, co-founder and president of the Cambodian Institute for Strategic Studies, told the Post over the phone he thought Cambodia’s decision was “unlikely to affect its relations with the US”.

Kung said it was still in the US and Cambodia’s “best interest to strengthen their ties, politically and economically”, adding that “strong relations don’t require both countries to take the same decision on every issue”.

Phay Siphan, spokesman for the Council of Ministers, said he was unconcerned about the possibility that Cambodia undermined ASEAN or weakened its relationship with the US.

“We belong to ASEAN, but every issue is different,” he said. “We do not work for US interests or Chinese interests, we work for Cambodian interests”.