Kuala Lumpur. East Timor’s prime minister told leaders of the Association of Southeast Asian Nations that it was a “dream realized” for his nation to be admitted to the bloc and an opportunity as it seeks to boost its struggling economy.

“Today, history is made,” Prime Minister Xanana Gusmao told the other leaders as the flag of East Timor, also known as Timor Leste, was added to the other 10 on the stage at a formal ceremony in Kuala Lumpur.

It was ASEAN's first expansion since the 1990s and was more than a decade in the making.

“For the people of Timor Leste, this is not only a dream realized, but a powerful affirmation of our journey -- one marked by resilience, determination and hope,” he said.

The ceremony marked the opening of ASEAN's annual summit, followed by two days of high-level engagements with key partners including China, Japan, India, Australia, Russia, South Korea, and the United States.

US President Donald Trump arrived Sunday in his first trip to Asia since returning to the White House, and was expected to sign a trade deal with Malaysia later in the day. Trump was also to take part in the signing of an agreement between Cambodia and Thailand, expanding a ceasefire that halted their border conflict earlier this year.

Chinese Premier Li Qiang, Canadian Prime Minister Mark Carney, and Japan’s newly inaugurated Prime Minister Sanae Takaichi are among more than a dozen other leaders expected to be on hand.

ASEAN membership brings East Timor, with a GDP of around $2 billion, better access to an economic community of nations with some 680 million people and a $3.8 trillion economy.

Malaysian Prime Minister Anwar Ibrahim, whose country holds the bloc's rotating chairmanship, said East Timor's accession “completes the ASEAN family, the affirming of our shared destiny and deep sense of regional kinship.”

He said ASEAN's goal was to “pursue growth that is both resilient and fair, and to safeguard the welfare of generations to come.”

The integration of the region’s youngest and poorest nation -- with just 1.4 million people -- demonstrates ASEAN's “inclusivity and adaptability, especially at a time of geopolitical flux,” said Angeline Tan, an analyst with Malaysia’s Institute of Strategic & International Studies:

"As protectionism is on the rise, the expansion of ASEAN demonstrates its commitment to regionalism, openness, and equal participation,” she said.

The last country to join ASEAN was Cambodia in 1999.