The Thai Foreign Ministry has tried to play down what has been seen as a partial boycott by ASEAN countries today of the ASEAN-US summit in which only three of the leaders of the regional grouping were present.

Besides Prime Minister Prayut Chan-o-cha of Thailand, only prime ministers of Laos and Vietnam attended the summit with US President Donald Trump’s National Security Adviser Robert O’Brien while the seven other ASEAN countries were represented by ministerial-level officials.

Kyodo News quoted a US diplomat as expressing US concern with ASEAN’s “intentional effort to embarrass” President Trump by partially boycotting  the summit.

“We are extremely concerned by the apparent decision” in relation to the Seventh ASEAN-US Summit, the diplomat quoted a US message to ASEAN as saying, according to Kyodo News.

The 10-member bloc has decided to downgrade part of its representation for the ASEAN-US summit in response to Trump’s decision to skip the event.

The decision was made during a working dinner Friday night during which “ASEAN foreign ministers decided to form a troika of three leaders only” to meet with O’Brien, according to diplomatic sources.

Foreign Ministry’s Spokeswoman Bussadee Santipitak said throughout 52 years of ASEAN’s existence, there were various situations that required the grouping to make adjustment to its meetings.

“So the format of meetings like this (ASEAN-US summit) has been something normal in our history.  And those meetings have proceeded smoothly and well,” she said.

She said ASEAN’s representation in this year’s summit was a joint stand taken by the grouping “by taking into consideration diplomatic protocol,” she said.

Bussadee also said that Thai Prime Minister Prayut attended the summit in his capacity as ASEAN chair while Vietnam is the next chair and Laos as ASEAN-US coordinator.

“But what is important is that all the ASEAN countries were represented in the summit,” she said.

Informed diplomatic sources said ASEAN leaders were unhappy with President Trump’s decision to stay away from the summit and his appointment of his national security advisor to represent him instead of someone more senior.

Since becoming president, Trump has attended only the ASEAN-US summit in Manila in 2017.  He was represented by Vice President Mike Pence in Singapore last year.