Besides participating in these two summits during November 14-15, Modi will also join the Regional Comprehensive Economic Partnership (RCEP) leaders' meeting and hold a bilateral meeting with USA vice president Mike Pence.
U.S. President Donald Trump's "America First" foreign policy and his resistance to multilateral agreements and institutions are viewed as an affront and a challenge in a region whose modern economies are largely driven by global trade.
Prime Minister Mahathir Mohamad of Malaysia, Myanmar Leader Aung San Suu Kyi, President Rodrigo Duterte of The Philippines, Prime Minister Nguyen Xuan Phuc of Vietnam, Prime Minister Lee Hsien Loong of Singapore, Prime Minister Prayuth Chan-ocha of Thailand, Sultan Hassanal Bolkiah of Brunei, Prime Minister Hun Sen of Cambodia, President Joko Widodo of Indonesia and Prime Minister Thongloun Sisoulith of Laos.
With the signing of a memorandum of understanding on the new logistics corridor, China and Singapore should build up the momentum and further boost connectivity, Li said. "It is now that we must continue to expand our intraregional trade and deepen the economic integration within ASEAN".
However, Duterte took steps to revive once-frosty ties with China after taking office in 2016 as he sought infrastructure funding and more trade and investment from Beijing.
"It (RCEP) is going to deliver real benefits to the people of our region", he said in an address.
China was now the standard bearer of global free trade, he added, with the 16-member RCEP deal at the heart of its strategy.
"This is not the time to close our doors by invoking trade protectionism measures", he added.
"Despite downward pressures we will not resort to massive stimulus", Li said.More news: National Football League moves Rams-Chiefs showdown from Mexico City due to field conditions
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Trade diplomats said negotiations will run deep into 2019.
Lee says officials have made significant progress but are unable to bridge all their differences.
India's concerns over opening its markets to competition, in particular from Chinese firms, has been a key obstacle in the several years of negotiations.
The participating countries will work towards the completion of RCEP talks by next year instead.
The TPP is still alive even without Washington - and will come into effect in December - but RCEP, if realised, will be the world's biggest trade deal.
As discussions over the RCEP trade pact drag on, another, rival accord, the dozen-nation Trans-Pacific Partnership, has been making headway despite Trump withdrawing the USA from the Pacific Rim free trade initiative three days after he took office.
The ASEAN summit, which formally opens Tuesday afternoon, will cover trade, maritime disputes and the Rohingya crisis.
Both US and China committed to supporting peace and stability in the South China Sea, the peaceful resolution of disputes, and freedom of navigation and overflight and other lawful uses of the sea in accordance with worldwide law during the dialogue, it added.The US takes no sides in the territorial disputes in the South China Sea but has expressed interest in the peaceful settlement of the rival claims.