US President Donald Trump has landed in Malaysia for the ASEAN summit, where he is set to witness an expanded ceasefire deal between Thailand and Cambodia and oversee pivotal trade talks.

Trump’s first order of business at the Association of Southeast Asian Nations summit will involve watching over a ceasefire deal between Cambodia and Thailand after he helped broker an end to a deadly five-day border conflict in July.

The agreement builds on a truce signed three months ago after Trump called the then-leaders of the two countries, urging them to end hostilities or risk their respective trade talks with Washington being put on hold.

Donald Trump and Anwar Ibrahim
Prime Minister Anwar Ibrahim greeted Donald Trump upon his arrival in Malaysia for the summit. (AP PHOTO)

Both sides blame each other for starting the five-day exchange of rockets and heavy artillery, which killed at least 48 people and temporarily displaced an estimated 300,000 people in their worst fighting in recent history.

Thailand’s Prime Minister Anutin Charnvirakul almost missed the signing after the death of the kingdom’s Queen Mother Sirikit on Friday, but later decided to fly in for the ceremony.

Trump was greeted by Malaysia’s Prime Minister Anwar Ibrahim and a troupe of ceremonial dancers when he landed at Kuala Lumpur International Airport. 

He stopped on the red carpet to dance with the performers before taking a US flag in one hand and a Malaysian flag in the other, and then jumped into his limousine to travel to the city with Anwar.

Anti-Trump demonstrations were also being held in Kuala Lumpur, with some protesters holding signs saying the president was not welcome in Malaysia.

As Trump mingles with other leaders, US and Chinese negotiators will meet on the sidelines to avert further escalations in a trade war between the world’s two largest economies.

Asked by a reporter if rare earths were discussed at the talks, which started on Saturday, US Trade Representative Jamieson Greer said a broad range of topics were discussed, including extending the truce on trade measures.

US Trade Representative Jamieson Greer
US Trade Representative Jamieson Greer is meeting Chinese officials on the sidelines of the summit. (AP PHOTO)

“I think that we’re getting to a spot where the leaders will have a very productive meeting,” Greer said.

Trump is also expected to discuss sharp US tariffs with Brazilian President Luiz Inacio Lula da Silva, who is among several world leaders attending the weekend summit.

Lula said he plans to argue that the 50 per cent tariffs imposed by Washington on Brazilian goods were a “mistake”, citing a $US410 billion ($A630 billion) US trade surplus with Brazil across 15 years. 

Trump signalled on his way to Asia that he was open to lowering the tariffs.

Asia’s youngest nation, East Timor, became the 11th member of the ASEAN bloc on Sunday, fulfilling a vision set out by its current president almost a half-century ago when the country was a Portuguese colony.

Also known as Timor-Leste, the country of 1.4 million people is among Asia’s poorest and hopes to see gains from integrating its fledgling economy, which at about $US2 billion ($A3.1 billion) represents only a tiny fraction of ASEAN’s collective $3.8 trillion gross domestic product.

East Timor’s accession follows a 14-year wait and although its membership is not expected to be transformative, it represents a symbolic victory for its President Jose Ramos-Horta and Prime Minister Xanana Gusmao, the heroes of its struggle for independence.