"If I can help mediate or arbitrate, please let me know", Trump said in comments at the start of a meeting with Vietnamese President Tran Dai Quang in Hanoi.
Duterte, however, said the Chinese leader would not back down on Beijing's territorial claim and justified his decision not to immediately demand Chinese compliance with a ruling by a United Nations -linked tribunal that invalidated China's sweeping claims in the South China Sea on historical grounds.
The official did not elaborate on the assurance made but said: "I think everyone not only China and the Philippines, the other claimants really want the South China Sea to be a sea of peace and stability and I think we will move forward on the Code of Conduct".
India has been supporting freedom of navigation and access to resources in the South China Sea in accordance with principles of worldwide law, including the 1982 UN Convention on the Law of the Sea.
Hanoi and Beijing agreed Monday to keep the peace in the sea, the countries said in a joint statement during a state visit to Hanoi by Chinese President Xi Jinping. Duterte took steps to thaw frosty relations with China after he won the presidency a year ago.
The statement is to be issued after the meeting between China and the 10-member bloc in Manila, a diplomatic source said.
The framework seeks to advance a 2002 Declaration of Conduct (DOC) of Parties in the South China Sea, which has mostly been ignored by claimant states, particularly China, which has built seven man-made islands in disputed waters, three of them equipped with runways, surface-to-air missiles and radars.
"While the situation is calmer now, we can not take the current progress for granted", said the draft, a copy of which was seen by Reuters.
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Such report will play an important role when countries take " Global Stocktake " under the Paris Agreement every five years. According, Chinese emissions are projected to rise by 3.5% in 2016 as compared to past year with its GDP up by 6.8%.
"There [sic] always playing - politics - bad for our country".
The media was ushered out of the venue before they could hear the response of the Australian Prime Minister.
Vietnam had been pushing for the code to be legally binding but ASEAN agreed in August that it would not have any legal force.
Turnbull also reportedly praised Duterte for his stance on the South China Sea issue and for how the government handled the recently concluded war in Marawi City, Lanao del Sur, against Daesh-inspired terrorists.
"They also talked about regional trade, with the Australian leader mentioning his country's huge potential especially because of its enormous market", the Palace statement said.
Unlike China, the U.S. is not a claimant to the potentially oil-rich and busy waters, but it has declared it has a national interest in ensuring freedom of navigation and overflight and the peaceful resolution of the disputes.
Since coming to office 16 months ago, the firebrand leader has been conciliatory to Beijing, despite a ruling by an global arbitration court favoring the Philippines in its territorial dispute with China.
The code framework is an outline for China and the ASEAN's consultations on a formal agreement.