After they spoke, Manila presidential spokesperson Ernesto Abella remarked, "We can say at this stage, that our relationship with the United States is improving".
On Wednesday Ambassador Marciano Paynor Jr, the summit's director-general for operations, told reporters, "As of now, President Trump, for instance, when President Duterte called him up to congratulate him, had already indicated that he is coming in November".
"Multilateral meetings of this sort, we usually expect 100 percent attendance", Paynor added.
After the retreat at the Coconut Palace, he said, the ASEAN leaders will return to the PICC for the rest of the meetings.
In a phone call in December previous year, President Duterte invited then President-elect Trump to the ASEAN Summit. The group's summit and related meetings will be held in Manila next week, the last week of April.
Indonesian President Joko Widodo and Sultan Hassanal Bolkiah of Brunei will visit the Philippines and have bilateral meetings with President Rodrigo Duterte in April.
Paynor elaborated on specific issues Duterte may discuss with Widodo.
"(Bohol) might as well be considered a well-fortified and (the) most secure place in the country right now", said DILG officer in charge Catalino Cuy, chair of the security committee of the Asean National Organizing Committee.
On April 26, a meeting of Asean Committee of Permanent Representatives will be held.
2017 is a full year for ASEAN and its current annual host, founding member-nation the Philippines.
Presidential Spokesperson Ernesto C. Abella said Mr. Duterte's South Korea trip is "not yet confirmed".
All 10 Asean leaders would then have the actual summit on April 29.
He also stressed the need for "fundamental freedom of navigation", and said he and President Donald Trump want to expand economic ties with Indonesia.
"In our security preparations, [we are] keeping in mind also the President's directive that we should not hamper or hinder the normal flow of daily activities here in the Metro Manila area".