Security and foreign experts see the Monday-Tuesday US-Asean summit in California as a promise from US president Barack Obama that the US will enhance relations with the key regional bloc, despite a coming change in US leadership.
Prime Minister Prayut Chan-o-cha along with other Asean leaders, with the exception of Myanmar president Thein Sein who cancelled at the last minute citing the political transition in his country, will meet for talks with Mr Obama in California's Rancho Mirage Monday.
The meeting venue is the Sunnylands Centre, known as the Camp David of the US West Coast, where the US president held talks with his Chinese counterpart Xi Jinping in 2013.
Although the two-day summit takes place in the final year of the Obama administration, Patrick Cronin, a senior adviser and senior director of the Asia-Pacific security programme at the Centre for a New American Security (CNAS) said Asean is seen as the focal point of Mr Obama's policy of rebalancing towards Asia.
It is the first time Asean leaders have met in the US during his term in office.
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Hosting Asean leaders is a breakthrough in the US leader's wish to institutionalise relations with the bloc, he said.
Prime Minister Prayut will return to Thailand on Thursday.
"Hosting Southeast Asian leaders in the United States is a milestone in that ambition which began by joining the Treaty of Amity and Cooperation," Mr Cronin said, referring to the agreement between Asean and non-bloc members that pledges to promote peace and goodwill.
They will meet Mr Obama in the first retreat on "Promoting Regional Prosperity Through Innovation and Entrepreneurship" on Monday afternoon, and again in the second retreat on "Protecting Peace, Prosperity and Security in the Asia-Pacific" the next morning.
Mr Cronin said Mr Obama should underscore the growing convergence of US-Asean security and economic interests rather than telling his Asean counterparts in general how his administration will further engage with Asean.
"The president's plan to attend the East Asia Summit in Laos -- the first time an American president will be visiting that country -- will underscore how far he has gone to transform US-Southeast Asian relations," he said.
Regarding terrorism and extremism, Mr Cronin and Pereira International CEO Derwin Pereira both said the US president should discuss a common strategy against terrorist threats even though the US cannot take part in operations in Southeast Asia.
They cited evidence of recent attacks in Jakarta as an example of active militant groups that have links to the Islamic State (IS).
IS seeks to establish a distant Caliphate in Southeast Asia, and Sunnylands could lead to the refinement of a common strategy against the terrorist scourge, they said.
Prapat Thepchatree, director of Thammasat University's Centre of Asean Studies said the US will expand the Trans-Pacific Partnership (TPP) as four Asean countries, Brunei, Indonesia, Singapore and Vietnam, have joined the trade pact.
"President Obama will use this opportunity to convince non-TPP Asean countries to redefine their position," Mr Prapat said.
However, he noted non-TPP Asean countries are likely to take more time to study the US-led trade pact and will not join any time soon since they are working on the Regional Comprehensive Economic Partnership (Rcep), in which China and Asean play the key roles.
The 12 TPP member countries account for 40% of global trade with a combined gross domestic product (GDP) of US$28 trillion, while the Rcep comprises 16 countries with a combined GDP of US$17.23 trillion (614.7 trillion baht).
Another commitment among the US and Asean leaders is protecting their countries against extremism, which threatens both regional and global peace and security.
Even though anti-terrorism cooperation will be a highlight at the summit, Asean will continue to keep a ''low profile'' to prevent the region from becoming a main target of the IS, according to Mr Prapat.
"Although the bomb attacks in Jakarta posed threats to the region, Asean has yet to take any prompt action against the extremist groups," Mr Prapat said, explaining Asean's adherence to a moderate approach.
According to a government source, the talks will also touch upon the process to establish a regional centre to counter messages of terrorism which have been agreed upon by the US and Malaysia.
The Kuala Lumpur-based centre will deal with propaganda messages by the IS which is known to use effective online messages to recruit members.
Aside from the new centre, Malaysia is also a home of the Southeast Asia Regional Centre for Counter-Terrorism (SEARCCT) which was initiated as a tool to tackle regional terrorism.
The Foreign Ministry's Asean Affairs department's director-general Jakkrit Srivali also expects Mr Obama to touch upon the sea disputes, saying the US leader wants to maintain a cordial atmosphere at the summit.
"The Asean leaders will urge the US to maintain good relations with other major powers in the region and expects the US to play a constructive role in all areas of our cooperation including security, economics and sustainable development," Mr Jakkrit said.
The expectation is for a warm welcome and constructive discussions between Mr Obama and Asean leaders, despite the limit in regards to US engagement with Thailand where they have been calling for a transition back to an elected government.