He opined that there was now more insecurity in Asia Pacific due to the absence of orderly framework for managing conflict and tension.
"In the South China Sea, for example, there is no rules-based order now, so we have more insecurity," he told Bernama, in reference to the South China Sea disputes involving both island and maritime claims among China and several ASEAN countries including Vietnam, the Philippines and Malaysia.
He earlier spoke on Asian views on America's role in the region at the APR themed, "The Future of the Asia-Pacific: Issues and Institutions In Flux".
Thitinan pointed out that ASEAN required not only the US, but also middle power allies and partners like Japan, Australia, South Korea and India to play a greater role in the region.
He said this was because ASEAN did not want to be too dominated by either China or the US as any imbalances of influence could bring possible tension that could lead to conflict, which was bad for the region's development.
"The region needs to rebalance itself to achieve a new balance for ASEAN among the major powers," he added.
On the new US administration, Thitinan said ASEAN hoped to see the continuity and consistency of US engagement under President Donald Trump.