NONTHABURI, Thailand (AP) -- Seven Southeast Asian leaders skipped an important meeting with the United States on Monday after President Donald Trump decided not to attend their regional summit in Thailand.
Rather than Trump, the U.S. sent recently appointed national security adviser Robert O'Brien to the Association of Southeast Asian Nations gathering. The move contrasts with other allies of the 10-member regional bloc who sent their heads of government.
Only host Prime Minister Prayuth Chan-cha of Thailand and the prime ministers of Vietnam and Laos joined O'Brien and the foreign ministers sent by the other countries.
The annual meeting of ASEAN leaders allows Southeast Asian leaders to deal as a group with the world's major powers, leveraging their influence in making security and trade arrangements.
The rise of China in recent years makes the meeting a field of rivalry between Beijing and Washington, which both seek to cement relations with a region of major geopolitical and economic importance.
That Trump chose not to attend and not send Vice President Mike Pence or Secretary of State Mike Pompeo to take his place left a diplomatic vacuum for other global leaders to fill, such as Japanese Prime Minister Shinzo Abe, Indian Prime Minister Narendra Modi and especially Chinese Premier Li Keqiang.
The meeting with the U.S., which takes place on the sidelines of the ASEAN summit, normally draws presidents and prime ministers. It could be perceived that by sending their foreign ministers the missing leaders were snubbing O'Brien, who Trump anointed his "special envoy" to the meeting just outside Bangkok.
"My guess is the leaders will attend the meetings when their counterparts are here," Philippine Finance Secretary Carlos Dominguez told reporters. "It's just a matter of proper balance."
During the meeting, O'Brien read a letter from Trump, who invited ASEAN leaders to a "special summit" in the U.S. early next year.
ASEAN is made up of Brunei, Cambodia, Indonesia, Laos, Myanmar, Malaysia, the Philippines, Singapore, Thailand and Vietnam. Together, they comprise a fast-growing regional market of nearly 650 million people.
At the annual gathering the ASEAN leaders meet in their own summit then separately meet their counterparts from outside the bloc including the U.S., China, Japan, Australia and India.
ASEAN leaders welcomed what they said was the conclusion of seven years of negotiations for a massive free trade deal called the Regional Comprehensive Economic Partnership. Officials, however, said there were still final issues to be resolved by the 16 countries involved in the trade deal before it can be signed early next year.
RCEP, which does not include the U.S., aims to level trade barriers between ASEAN members and six other countries in a bloc encompassing roughly a third of all global trade.
ASEAN also reported progress in negotiations to craft a so-called "code of conduct" with China that aims to prevent armed confrontations in the disputed South China Sea.
Four ASEAN states — Brunei, Malaysia, the Philippines and Vietnam — along with China and Taiwan, are involved in the long-simmering territorial conflicts in the sea, a key waterway for global commerce. Dwarfed by China's military, rival claimant states have looked at the U.S. as a counterweight to the Asian powerhouse.
During the meeting with his ASEAN counterparts, O'Brien made a swipe at China, saying Beijing "has used intimidation to try to stop ASEAN nations from exploiting their offshore resources, blocking access to $2.5 trillion in oil and gas reserves alone. These tactics go against the rules of respect, fairness and international law."
"The region has no interest in a new imperial era where a big country can rule others on the theory that might makes right. America is helping our ASEAN friends uphold their sovereignty," he said.
China has long warned Washington to stay away from the territorial disputes it regards as a purely Asian issue. It has also opposed naval and aerial patrols by the U.S. and its allies in the disputed waters, but American forces have maintained their presence and continued "freedom of navigation" sail-bys designed to challenge China's vast territorial claims.
Last year, Trump sent Pence to the ASEAN summit. This year, both he and Pence were busy campaigning.
In addition to O'Brien, U.S. Commerce Secretary Wilbur Ross also traveled to Bangkok with a trade mission that is touring the region.
Despite the apparent downgrading of the ASEAN gathering by Trump, U.S. businesses and government were seeking to emphasize the American commitment to the region with a privately led conference attended by about 1,000 business and government officials.
"The Trump administration is extremely engaged in and fully committed to this region," Ross told the meeting.