While it was still hard to see what the Trump administration wanted to do regarding the relationship with Asean, it was expected that the US would continue to see Asean as a useful partner, said Denny Roy, senior research fellow at the research and education institute.

While many mainland Asean countries have strong economic ties with China, many maritime states are at loggerheads with Beijing over territorial disputes in the South China Sea.

Of the 10 members, Brunei, Malaysia, the Philippines and Vietnam claim sovereignty over islands, rocks, shoals and reefs in the contentious sea. Indonesia is not a claimant but has some conflicts over fisheries.

The US, which is not a claimant in the area, has championed freedom of navigation as well as urged Asean to speak with one voice in dealing with China.

“Asean will continue to be under tremendous pressure, being pulled and grasped by China on the one hand and the US on the other, with the South China Sea issue among the issues,” said Roy.

While the Trump administration wanted to make its presence felt in Asia, notably with close relations with China, former US diplomat Raymond Burghardt said the current administration in Washington, including Trump and his advisers, had relatively little experience in dealing with Asian affairs, much less Southeast Asia in particular.

Key people who will deal with Asia, such as Secretary of State Rex Tillerson, have more knowledge about the Middle East, Burghardt said.

People on the security side, such as Secretary of Defence Jim Mattis, have spent their careers also focusing on the Middle East, he said.

“This administration has not yet set its strategy and nobody knows what the strategy is,” Burghardt told Asean journalists. “You will hear so-called strategies from individuals that sometimes contradict each other.”

Burghardt, former US ambassador to Vietnam and deputy envoy to the Philippines, said Vietnam needed to take a crucial role in leading Asean to deal with China regarding the South China Sea as the Philippines seemed to be taking a softer stance to please Beijng.

“Vietnam is very carefully and politely starting to play more of a role, even a leadership role in Asean,” he said.

From the point of view of a former career US diplomat, it was a positive development, he said. “Vietnam has a lot to contribute, in terms of providing a coherent voice and viewpoint in Asean.”