Trump says the trip has put the world on notice that the "rules have changed" for countries that want to trade with the U.S.
President Trump looked slightly ill at ease at first but then appeared to enjoy himself during the unusual handshake with Prime Minister Malcolm Turnbull, Russian Prime Minister Dmitry Medvedev, Vietnam's Prime Minister Nguyen Xuan Phuc, Thailand's Prime Minister Prayut Chan-O-Cha, Philippine President Rodrigo Duterte, Singapore's Prime Minister Lee Hsien Loong.
"The reason I like the Boeing is because it's jobs for the United States", Trump said.
In a news conference after flying back here after midnight yesterday, Duterte said Xi assured him of China's peaceful intentions in the strategic waterway, where Beijing, the Philippines, Vietnam and three other governments have overlapping claims.
Trump and Putin were expected to hold a formal meeting on the sidelines of the summit.
Trump raved about his accomplishments on his five-nation journey, including on trade and North Korea, but said he would wait until his return to Washington on Wednesday to elaborate with a "major statement".
As regards the South China Sea, the official said there has been a "very clear" and "consistent message" from Trump on freedom of navigation in the South China Sea. He was closing a almost two-week trip through Japan, South Korea, China, Vietnam and the Philippines that included one-on-one meetings with the leaders of those nations during which he stressed trade.
Since he became president, thousands have died in a nationwide anti-drugs campaign that human rights defenders say is being carried out in a culture of legal impunity.
With that curtailment, it seems even less likely that Trump will call on Duterte to suspend operations and seek justice for victims.
"The arms that you sent were very accurate and they were able to take care of the snipers", Duterte told Putin, referring to the ISIS-inspired Maute rebels. And nearly all of them also have the same problem.
He urged the region to reshape its trade deals to America's liking, declined to spotlight violent human rights abuses and cranked up pressure on North Korea.
Hours after being sworn in as Philippine president, Duterte goes to a Manila slum and urges residents to kill drug-addled neighbors.
As the death toll from his drug war nears 1,000, Duterte vows no let up. Press secretary Sarah Huckabee Sanders said human rights issues were "briefly" discussed. Government officials estimate that well over 3,000 people, mostly drug users and dealers, have died in the ongoing crackdown.
Asean and China also highlighted the role of witnesses in identifying and prosecuting corruptors and said they would develop "an effective protection system for witnesses in corruption cases, where appropriate". Human rights groups believe the total could be closer to 9,000. "The relationship with the past administration was awful, to use a nice word".