And Duterte has been consistent in saying that the people who claim that the Manila government was behind the killings have been relying only on reports that have not been verified, from supposed human rights advocates who are really pushing an anti-Duterte agenda.
"Given our history here, the U.S.has a moral obligation to help Laos heal", Obama said.
He has also taken a more conciliatory position with USA rival China.
Diplomats say strains with longtime ally the Philippines could compound Washington's difficulties in forging a united front with Southeast Asian partners on the geostrategic jostle with Beijing over the South China Sea. More than 2,000 suspected drug dealers and users have been killed since Duterte launched a war on drugs after taking office on June 30.
"There is a need for us to closely follow these developments and continue to enhance ASEAN cooperation and collaboration with the global community", he said.
The Philippines did not comment publicly on the cancellation until about nine hours later, when Duterte's statement said that both sides had "mutually agreed to postpone" the meeting.
That caused a reaction heard around the world by the Philippines President Rodrigo Duterte, calling President Obama either a "son of a bitch" or the "son of a whore" depending on your version of the translation.
Obama has not mentioned him so far in his public remarks, but Rhodes said that "we care very deeply about her case and her husband, and we believe she deserves to know what happened to her husband".
"The Philippines is not a vassal state", he said.
President Barack Obama says the US commitments to the Asia-Pacific region will endure over the long term.
Based on a statement read Tuesday by Presidential Spokesperson Ernesto Abella on behalf of President Duterte, the meeting between the U.S. and the Philippines has been mutually agreed upon to be moved to a later date.
Obama indicated Monday he was wary of meeting with Duterte, suggesting the bombast could prevent making substantial progress between the two nations.
Philippine President Rodrigo Duterte arrives Monday in Vientiane, Laos, for the ASEAN Summit.
The meeting would have been the first between the two presidents. "There will be a pool spray at the bottom of this meeting", said National Security Council Spokesperson Ned Price in a statement.
Earlier Tuesday, Duterte expressed regret over his "son of a bitch" remark while referring to Obama, in a rare display of contrition by a politician whose wide arc of profanities has unabashedly targeted world figures including the pope.
Sure, Duterte could use a little more prudence and lose a lot of the gutter-speak, especially when talking to the press and about foreign leaders. In a statement read out by his spokesman, Duterte said his "strong comments" to certain questions by a reporter "elicited concern and distress, we also regret it came across as a personal attack on the USA president".
The audience just chuckled in reception to Duterte's comment, which was about terrorism in general, the Jakarta Post reported. "You just can not shoot a statement against the president of any country".
This isn't the first time that President Duterte has caused controversy through his language. The pro tempore leader of the Senate, Franklin M. Drilon, for his part said: "Unfriendly rhetoric and undiplomatic statements will not bring us anywhere".
The White House says the USA has contributed $100 million to the effort in the last 20 years.
Still, Mr. Duterte can be a pragmatist, he said, and "regularly tones down his bombastic rhetoric when necessary". And that message, quite simply, is that the Philippines and its government should be allowed to do what they think is good for them, without unwanted intervention from foreign powers like the US.
China's assertions to the area, where it has reclaimed thousands of acres of land and boosted its naval presence, are often a focus of Asean summits as they overlap those of Vietnam, the Philippines, Brunei, and Malaysia.
Check out my columns on how we lost Panatag Shoal, which was the reason given by Aquino and del Rosario when we filed the Arbitration Case against China on its territorial claims in the South China Sea. China should not hold too many illusions. But the US-Philippine alliance will remain solid.
"That conflict was another reminder that, whatever the cause, whatever our intentions, war inflicts a bad toll, especially on innocent men, women and children", Obama said.
I had a first-hand experience of our subservience to the USA when former President Gloria Arroyo asked her small circle of advisers, which included me at that time, to discuss whether to join the United States demand that we join the absurdly named "Coalition of the Willing" that supported the American invasion of Iraq in 2002.
During the Vietnam War, the United States dropped an estimated 270 million cluster bomb submunitions on Laos, part of a "Secret War" to cut off a supply chain to North Vietnam. The human rights issue has brought enmity between the United States and its two allies of Turkey and the Philippines. "Not personal", he said.