A Palace official confirmed that the younger Duterte, known as Baste, is part of the delegation. There are also photos of him inside the presidential plane posted by fellow passengers on their social media accounts.
Baste is not the only Duterte family member joining the trip. Also in Moscow is the President's partner Honeylet Avanceña and their 13-year-old daughter Veronica or Kitty.
This is the second time Honeylet and Kitty are joining the President on an overseas trip. They previously accompanied him during his back-to-back Cambodia, Hong Kong, and Beijing visits, earlier this month.
Baste, 29, is Duterte's youngest son with his former wife Elizabeth Zimmerman. Baste's older siblings are Davao City Mayor Sara Duterte-Carpio and Davao City Vice Mayor Paolo Duterte.
Despite being in a family of government officials, Baste has, for the most part, stayed away from politics. But he helped out during his father's 2016 presidential campaign, speaking to youth groups and attending sorties.
Baste owns a junk shop business and is fond of surfing.
His father has chastised him publicly, calling him out for supposedly never visiting his children. Baste has two young children with different women. – Rappler.com
Pia Ranada covers the Office of the President and Bangsamoro regional issues for Rappler. While helping out with desk duties, she also watches the environment sector and the local government of Quezon City. For tips or story suggestions, you can reach her at firstname.lastname@example.org.