Bolivar said Philippine Foreign Secretary Enrique Manalo will fly to Washington DC in May for the ASEAN-US Foreign Ministers' Meeting.
Moreover, Trump would be gracing the event, European PPP Expertise Centre alias EPEC Summit scheduled to be held in Vietnam.
The DFA will host the 30th ASEAN Summit and Related Meetings from April 26 to 29.
"Multilateral meetings of this sort, we usually expect 100 percent attendance".
The East Asia Summit groups 18 countries including ASEAN member states, the US, Russia and China.
Duterte's public animosity towards the U.S. appears to have softened under Trump's administration, with the firebrand leader praising the property-mogul president as a "realist" deep thinker over the weekend.
According to Paynor, of the 17 ministerial meetings, only eight have been finished out so they still have nine more meetings which need suppliers.
"So at least verbally he (Trump) said he was coming", Paynor said.
Obama called off what was meant to be his first meeting with Duterte after the latter reportedly cursed at him, and even described him in vulgar terms.
Still, Bolivar said in a text message, "The progress on the discussions on the framework may be discussed if any of the leaders bring it up".
Several activities will happen on the 28th, including the Indonesia, Malaysia, Thailand Growth Triangle Senior Officials Preparatory Meetings, the Asean Business Advisory Council Prosperity for All Summit; we have the 14th Asean Leadership Forum; the Asean Foreign Ministers Meeting; the 15th Asean Political Security Council Meeting; and the 19th Asean Coordinating Council Meeting.
Presidential Spokesperson Ernesto C. Abella said Mr. Duterte's South Korea trip is "not yet confirmed".