On Monday, just three leaders from the 10-member Association of Southeast Asian Nations (ASEAN) showed up to the meeting with US National Security Adviser Robert O’Brien, who was leading the US delegation at the summit in Thai capital.
In attendance were the prime minister of Thailand, which is hosting the summit, along with the leaders of Laos and Vietnam, Presstv Reported.
Video from the event showed seven foreign ministers sitting at a table usually reserved for head of states.
"It's not appropriate for ASEAN to send leaders when the US representation is not on parity," media outlets quoted an unnamed diplomatic source in Bangkok as saying
Washington sent a relatively low-level delegation to the weekend ASEAN summit - a decision that was widely perceived as a snub, given that other top leaders were present.
A senior White House official said that Trump could not come this year because he was busy with campaign events back home.
The US has reportedly taken issue with what it saw as ASEAN leaders’ “intentional effort to embarrass” President Trump at the summit.
This is the second year in a row that Trump has skipped the summit. Vice-President Mike Pence attended last year's meeting in Singapore.
The Asean leaders’ decision to send their respective foreign ministers to the Asean-US summit could be interpreted as “a strong rebuke of US inattentiveness to the region”, noted Tang Siew Mun, who heads the Asean Studies Centre at ISEAS - Yusof Ishak Institute.
“In light of the diplomatic fiasco in Bangkok, the invitation may be viewed as a ‘consolation prize’ for Trump’s no-show at the Asean-US Summit and East Asia Summit,” Tang said.
At other events during the summit on Monday, members have rallied against protectionism amid fears of dragging global growth made worse by the US-China trade war.
This comes as 35th summit of the ASEAN and related meetings were underway in Bangkok, with a focus on multilateralism and connectivity.
The Sunday session commenced with a speech by Thai Prime Minister Prayut Chan-o-cha, who called for supporting the China-backed Regional Comprehensive Economic Partnership (RCEP) in order to create a prosperous and sustainable region.
Established in 1967, the ASEAN group is comprised of Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam.
Heads of 10 ASEAN countries and six of its dialogue partners — namely Australia, China, India, Japan, South Korea and New Zealand — are scheduled to meet on November 4 for their third RCEP summit and the closing ceremony.
The 16 countries account for a third of global gross domestic product and nearly half the world's population.
China proposed the RCEP shortly after US President Trump pulled the US from the Trans-Pacific Partnership (TPP) — which would have been the world’s largest trade deal.
The pact, which will be the world’s biggest free trade deal, is expected to cover about a quarter of the world’s exports.
It is also aimed at breaking down trade barriers and promote investment to help emerging economies catch up with the rest of the world.