The Association of Southeast Asian Nations will press for trade multilateralism and deeper ties with new partners, while managing the fallout from Trump's global tariff offensive at its annual meeting in Malaysia's capital.

Trump will be in Kuala Lumpur on Sunday to begin a five-day trip through Malaysia, Japan and South Korea, aimed at bolstering his diplomatic credentials, as US and Chinese officials work to avert a trade war escalation ahead of his planned meeting with China's President Xi Jinping in South Korea next week.

Leaders will gather on Sunday ahead of engagements with partners including Trump, Chinese Premier Li Qiang, Brazilian President Luiz Inácio Lula da Silva, South Africa's Cyril Ramaphosa and Japan’s newly elected Prime Minister Sanae Takaichi.

"This represents a new strategic direction for Malaysia and ASEAN in expanding diplomatic and trade ties with other regions, including Africa and Latin America," Malaysian Prime Minister Anwar Ibrahim, the summit's host, said on Wednesday.

ASEAN, which also includes Brunei, Cambodia, Indonesia, Laos, Myanmar, the Philippines, Singapore, Thailand, and Vietnam, will formally welcome East Timor as its 11th member on Sunday.

Commonly known as Timor-Leste, its accession to ASEAN is seen as a political win for one of the world's poorest countries, though analysts say the economic benefits remain uncertain.

ASEAN's regional outreach comes even as its unity remains tested by internal disputes.

Border tensions between Thailand and Cambodia erupted into a deadly five-day conflict in July, killing dozens of people and temporarily displacing about 300,000 in their most intense fighting in recent history.

Malaysia helped secure an initial ceasefire on July 28, aided by decisive calls from Trump to the leaders of both countries.

Thai Defense Minister Natthaphon Narkphanit said this week the two countries have made "meaningful progress" on a broader ceasefire agreement, which will require both sides to remove all mines and heavy artillery from their borders.

The deal is expected to be signed on Sunday in the presence of Trump, Malaysian officials said.

ASEAN, however, remains split over how to end a deadly civil war in Myanmar sparked by a military coup in 2021.

Fighting has intensified despite repeated calls for de-escalation, with ASEAN making little progress in getting Myanmar's military rulers to adhere to a peace plan it agreed to months after the coup.

ASEAN foreign ministers will discuss on Friday whether to send regional observers to Myanmar's general election, Malaysia's Foreign Minister Mohamad Hasan said this week.

Critics have derided the election, set to begin in December, as a sham exercise to legitimize military rule.

Trump is expected to be accompanied on his Asia trip by top US officials, including Secretary of State Marco Rubio, Treasury Secretary Scott Bessent and Trade Representative Jamieson Greer.

Bessent and Greer plan to hold talks with Chinese officials in Malaysia to iron out issues ahead of the meeting between Trump and Xi, after Beijing expanded export curbs on rare earths. China said the talks with its vice premier He Lifeng will run until October 27.

Trump said he expected to reach agreements with Xi that could range from resumed soybean purchases by China to limits on nuclear weapons.

Trump could also meet with Brazil's Lula in Malaysia, sources have said, as Rio looks to lower hefty US tariffs on Brazilian goods.

Washington's levies are expected to remain high on the ASEAN summit agenda, with Southeast Asian foreign and economic ministers due to hold a joint meeting for the first time in the bloc’s history on Saturday.

The United States has imposed tariffs of between 10 percent and 40 percent on Southeast Asian imports, with the majority of ASEAN countries hit with a 19 percent rate.

The countries will seek to formalize trade deals with the United States with Trump present, Malaysian officials said.

Malaysia also plans to host a gathering of leaders of the Regional Comprehensive Economic Partnership, the world's largest trading bloc, on the sidelines of the ASEAN summit.

The RCEP, which includes all ASEAN members as well as China, Japan, South Korea, Australia and New Zealand, is touted by some analysts as a potential counter to US tariffs, but it is considered weaker than some other regional trade deals due to competing interests among its members.